Temperature variable comsol. T variable, click the Go to Source button (), .

Temperature variable comsol In some cases, different dependent variables are used to compute the temperature in the wall, at the wall sides, or in the turbulent boundary layer. It calculates the average temperature over the domain and you can use this as a varaible. I simply change the Jc and alpha from parameters to where [t_0,t_1] is a time interval, \Omega is a spatial domain, and F(u) is an arbitrary expression in the dependent variable u. My suggestion is that you design a 1D model for which you already know the analytical solution (Somthing like heat transfer through a wall with convective heat transfer at one side and known temperature at the other side). 15 K by default) and all temperature variables from the To make the COMSOL Multiphysics software interpret 1 00[degC/K] as an absolute temperature, split the expression using two separate expressions such as 100[degC][1/K], which equals 373. This is the centerline temperature of the beam, controlling the axial part of the thermal expansion. This is relevant on fluid inlets where the temperature condition should not be enforced on the walls at the inlet extremities. 1 7 Replies . I guess you can use non local coupling 'Average'. In this article, we discuss how to perform this specific type of multiphysics coupling Temperature dependent variables - Circular variable dependency detected. (the minput. I notice that COMSOL has several built in materials with properties defined as a function of temperature (or any other input variable for that matter). . Calling temperature variable at specific locations to define new global variable. 3b 4 Replies How I can appropriate / set a variable for temperature distribution on border? Posted Sep 26, 2011, 3:51 a. In this process, the latent heat increase due to evaporation is balanced by Hi Sahitha, It is possible to assign a temperature to a point, but it is not recommended because you introduce a singularity in the model. Domains. It is obtained by adiabatically reaching saturation state for a sample of air with initial water vapor pressure p v. How I specify the location (Edge or Surface or Point) and How I generate the temperature graph as a function of time? Many Thanks in Advance. e "T", "T2", "T3" this holds also if you later delete one of the physics, the name remain. Posted Jan 27, 2015, 4:37 p. Please login with a If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help. In essence, this is a boundary condition dependent on the dependent variable (T) which is also dependent on position. I would like to define some temperature-dependent variables in my model. For example, a Convective Heat Flux boundary condition on a heated body computes the heat flux based on a heat transfer coefficient and the temperature difference to the surroundings. In COMSOL I am working on a transient thermal model in which the temperature cycles from a lower temp to a higher temp repeatedly, with a set of temperature dependent variables. Hello. condInd, over time (right). Nor does it appear in any of the PDF documentation that I have searched. The applied heat flux is turned on or off based upon a minimum To edit the Temperature field, click Make All Model Inputs Editable (). I attempted to define the thermal conductivity as a global variable, but the expression is in orange and is coming up as an "Unknown function or operator" when assigned to the material, Always check your dependent variables when you add physics. Hi Kaleem, Bulk temperature evaluation. The COMSOL Multiphysics software connects the model input to an existing field (dependent variable) within the physics interface (but not to available fields in other physics interfaces). Created Date: 1/8/2024 2:45:26 PM With the release of version 5. (R_const*T), where T is the temperature, and R_const in a built-in physical constant for the universal gas constant. Hi Ivar, Thank you very much for your reply. This corresponds to the variable minput. 15 K by default) and all temperature variables from the physics A pair has to be created first. For example I have the "T" variable in my equation for temperature but I want Comsol to put temperature value as it calculates it along the pipe wall. under Values of variables not solved for in the Settings window for the study, by its (fixed and constant) initial expression, The problem comes when I try to keep this temperature always at 37ºC, because I am defining an initial value of 37ºC but when time passes, The Model Input section reflects that the temperature is defined from the Heat Transfer in Solids interface. T that is required to calculate the liquid's dynamic viscosity. PST MEMS & Nanotechnology, Heat Transfer & Phase Change, MEMS & Piezoelectric Devices, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4. PDT Heat Transfer & Phase Change, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4. Specific Heat (Cp) is looked up with an interpolation function in which fluid temp and pressure are arguments [eg. 4, Version 5. EDT Heat Transfer & Phase Change, Parameters, Variables, 2) select the time series 2 dependent variables of Solver Configuration - Solver 1 - Dependent Variables 2 (Time series 2) and set them to refer to "Solver 1", for bot values solved for an not solved for 3) compute 4) in the new plot group write T-T0 for the display temperature increase 5) Duplicate the Plot group and write T2-T0 for this COMSOL Multiphysics Temperature variable for up (top) and down-sides (bottom) of the thin layers. As an example I have heat loss in conductor, insulation and sheath. Comsol calculates the temperature on the wall but how can I use that each point temperature as a variable to calculate heat transfer coefficient (h) which is a function of wall temperature. Includes exercise files. i need to create a velocity for the moving mesh, this velocity takes the temperature value at (r=0) in the (2D axisymmetric model) and multiply it by a simple exponential function of r to give a velocity variable along a boundary. If you define the expression for the coefficient of thermal expansion yourself, you must ensure that it depends on a ‘free’ variable, and not use the same temperature variable as you use to prescribe the current How to apply variable temperature boundary Condition. However, when I do the calculations, I have the strong impression that, instead of integrating all the CTE values between the strain reference temperature Tref (in the Thermal expansion coupling) and the final temperature Tfinal (set by means of a Temperature constraint applied on all the boundaries), only CTE(Tfinal) is considered, and the strain is calculated as Hi Junfeng, You can add an Average operator from the Definitions>Nonlocal Couplings menu. This way, we can work on something else while the software checks the conditions after each we use the comp1 name scope to identify both the maximum operator and the temperature variable T. PST Fluid & Heat, Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD), Geometry, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4. It will be included in the coming release, COMSOL Multiphysics 4. COMSOl has now in v4. Model Input. For example, say you solve for temperature, T, and you have a Maximum coupling operator, maxop1, then use: maxop1(T,x) for the x-coordinate at which the maximum occurs It is called with the two integration limits being the reference temperature < phys>. g foo) that follows exactly your desired temperature with time profile. Power is delivered as a pulse. In the field defining the equation, we will use an Integration Coupling Operator named intop to integrate the normal total energy heat flux variable, ht. Hi if you need to get (as a global value/variable i. Posted Sep 29, 2022, Dear All I have to apply temperature boundary condition which is varying from 10 deg to 40 deg in 90 min. Name. To edit the minput. Hi From my understanding, when you fetch a library material data set it's loaded when you do the operation in the BC GUI, you see he values entered in BOLD, but then you can always change or adapt some of them, or complement others not defined. The expansions (strains) in the I am using comsol 5. 1 module. I want to simulate a time dependent temperature distribution for a simple geometry what i attached here and want to see the temperature changes over the whole domain. EST 0 Replies . These are items defined under Component 1, For this I would use the "Options - Extrusion Coupling Variables - Boundary Variables" I select the source boundary "1" along r=0, define a Name i. For User defined enter a value for the External Temperature T ext (SI unit: K). By default the Common model input is used. Which expression do I have to put instead of T. I want to define h as a function of wall temprature which is calculated by comsol heat transfer module) Note- I am using COMSOL 4. Temperature at a point plotted over time. 5 of the COMSOL Multiphysics® software, there is a feature for tracking the state, or history, of your model. PDT. In this case T Learn how to implement boundary conditions and constraints for variational problems in COMSOL Multiphysics®. The Discontinuous Galerkin constraints option is especially useful to prevent oscillations on inlet boundaries where convection dominates. I have attached a simplified version of my problem. I simply change the Jc and alpha from parameters to Using source and destination maps to define implicit relations between source and destination coordinates in a General Extrusion operator. now in order to do transient study of heat transfer phenomenon I need to consider both electron (Te) and Lattice temperature (Tl) of the system. I tried to use the maxop1 operator with the sintax 14*(maxop1(T2)<100[degC]), where 14 is electrical potencial (14V) and T2 is temperature variable, but To monitor the average temperature of domain within a model, use an average component coupling operator, as described in Knowledge Base 913: Computing Time and Space Integrals along with a variable that stores the average temperature, as shown in the screenshot below. See Identity and Contact Pairs in the COMSOL Multiphysics Reference Manual for more details. Posted Jul 28, 2014, 3:49 p. 15 K by default), and all temperature variables from the On the material frame, the density is evaluated onto a reference temperature to ensure mass conservation in the presence of temperature variations. how do i input thi sin comsol? please help. 4 2-D axis-symmetric geometry. Cp(T_fluid, P)]. Defining Temperature-Dependent Variable in Comsol. This node adds several conditions for temperature exchange at the interfaces of an isothermal domain. This enables you to: See how the variables are calculated by the software; See the names of variables and the quantities each one defines; Access and use the variables when formulating expressions Animation of the temperature distribution as the prescribed temperature spot travels along the bar. A pair has to be created first. When it is irradiated with femtosecond laser pulse, it gets heated. T - Feature: Time-Dependent Solver 1 (sol1/t1) Any thoughts on how to couple an ODE that defines a new variable with a variable already defined in COMSOL, in this case Temperature=T. Figure 10. 1) you impose the temperature T on the common boundary, that is not required, COMSOL considers such an internal boundary as a boundary with continuity on any flow, including heat flux. I defined them under "Global definitions - variables". Therefore you might have either 2 "T"'s or its "just" that xyour temperature variable is T2 and not T as you thought--Good luck How to create variable for temperature, current and voltage in a model . Application ID: 100401. See Theory for Harmonic Heat For that I need temperature as a variable so that I can use following function max(sign(T-Tm),0) =>for 0 its solid and for 1 its liquid But the problem is how can I define temp I am designing a heat exchanger in Comsol without actually modeling the fluid. For example: Name: E Expression: 500*T - 200 [Pa] I am trying to add this variable as a function of T in COMSOL>Model builder>definitions>parameters. this seems to be a simple ting to do i a code, but comsol for some reason does not accept this and require me to define the temperature That is the variable that you enter where the control variable should act, such as an inflow velocity or a heat source that affects the measured value that you want to control. For example: Name: E Expression: 500*T - 200 [Pa] With the release of version 5. pp1mat1. If you instead define the variable under Model 1>Definitions, it will recognize T and you will not see the orange color that indicates a problem with the variable (the tooltip says "Unknown variable From the Temperature T list, select an existing temperature variable from a heat transfer interface. The observed values are processed by computing weighted means, standard deviations, maximum, All these conditions are illustrated in Figure 3-8 for the variation of the dew-point temperature over 1 year at New York/John F. EDT Heat Transfer & Phase Change, Parameters, Variables, & Functions Version 4. If you still need help with COMSOL and have an on-subscription license, please visit our The wet bulb temperature is also represented on Figure 3-1. I am designing a heat exchanger in Comsol without actually modeling the fluid. def. Only edges (3D) or points (2D and 2D axisymmetric) adjacent to the boundaries can be selected in the parent node. T variable, click the Go to Source button (), Some of these sections may be empty if none of the properties given in that node has a temperature dependence. ? Actually i want to see the temperature distribution over a time on certain material in a preset heated environment (say If you want to define a variable that is spatially variant, use the local Variables node under the local Definitions node (under Component 1). Tvar contains either the temperature upside or downside the boundary. I select "General transformation" and use "z" as source transformation variable (COMSOL help: might I use s ?). I just have a temperature as model input. The constraint is The available options are User defined (default), Common model input (the minput. In your BC you can use an if condition I am new in COMSOL and trying to run a simple heat transfer simulation in COMSOL (heat transfer in solid module). Each of them are temperature dependent. How could I do this in COMSOL? Thanks!-- As an example, you can access the variable named tflux using ht. Then define it on the boundary (surface) where you want to compute the average. This is messy. The problem is that I am wondering how the temperature is defined if I run a simulation. Temperature on up (top) and down- sides (bottom) of the thin layers. T - Global scope: Failed to evaluate expression. Saturation Pressure. What is bad? Thank you. The heat transfer equations are solved for the In the same way I create the Options - Integration coupling variables - sub-domain variables: "Area2" = int(1,dx*dy) on sub-domain 2 the temperature sensor, this variable is simply the area of my surface, and I have defined the "T2ave" = int(T/Area2,dx*dy), the average temperature over the boundary 2 = the termometer readout. For the pressure vessel case, the temperature is cycled between 500°C and 600°C, as shown in Figure 11. Ambient Variables and Conditions. With the conjugate heat transfer solution, you can use the built-in April 16, 2024 COMSOL Employee. Relative Humidity. Hello, I have a conductivity function about insulation materials given by 3D curve fitting from experiment each DC electric field and temperature. Haolin Zhu . Posted 09. The Dependent Variables node handles initial data and scaling for the dependent variables that you solve for as well as how to compute dependent variables not solved for. Closing Remarks on Modeling Materials with Thermal Hysteresis. - Expression: comp1. Assign it to a point in the geometry (which you can create by adding a Point geometry object), and then I am new to COMSOL, and i am trying to model of ac losses in HTS cable. I have to input the external temperature of the chiller/ temperatuer of the cool air. To do this, I have include files with constant (temperature-independent) and How to fix the problem of non-integer exponent and temperature dependent variables. These variables can also be used to affect other fields, such as material properties, and can thus be used to implement hysteresis into your model. This section describes when additional degrees of freedom are needed and how I would like to define some temperature-dependent variables in my model. The ambient temperature decreases from +4 C to -30 C. tflux (as long as the physics interface is named ht). Velocity streamlines. 3a 1 Reply Undefined variable. How to apply such boundary condition please suggest me? 1 Reply Last Post Note that while COMSOL employees may participate in the discussion On the material frame, the density is evaluated in relation to a reference temperature in order to ensure conservation of the mass in the presence of temperature variations. If you know the density as a function of temperature, you can write the temperature in the first column and the density in the second. On the material frame, the density is evaluated onto a reference temperature to ensure mass conservation in the presence of temperature variations. change in thermal conductivity with respect to temperature . First, enter the mathematical expression that defines the function. This variable does not appear in the Equation View node. If I let a certain current through the conductor a certain temperature set in each area of the cable. I am dealing with heat transfer of a food product placed in a blast chiller. EDT Parameters, Variables, So, if you do not know the temperature, you must know something about the heat The Common model input option corresponds to the minput. How to apply such boundary condition please suggest me? Learn how to manually set the scaling of variables when modeling in COMSOL Multiphysics® with step-by-step instructions, screenshots, and exercise files. My question is, if it is possible to set the temperature in an area as a variable if the heat source is dependent on the temperature. See Identity and Contact Pairs in the COMSOL Multiphysics Reference Manual You can define a function (e. 1 Reply Last Post Jul 25, 2018, 4:07 a. Posted Mar 3, 2023, 2:35 p. When COMSOL plots the temperature, the temperature of the fluid in the upper part just dissapears – I defined the solid in the chamber as a heating source, but the heat is not transfering to the rest of the model. But i get stucked on one thing, i didn't able to create a variable for temperature, voltage and current and also, i don't Hi everyone, I have a block in variable ambient temperature. Cheers, It is called with the two integration limits being the reference temperature < phys>. - Variable: comp1. set up a funciton for your variable and enter this after you have loaded the material, or what I often do, in my In the Model Builder click the Temperature node. Yes it is one domain, let us say we have a material with some dimension in 2D. But when the powder reaches the melting point, its material properties should change to the properties of the bulk material, independent of the following temperature. EST Materials, Parameters, First off this this is my first real project in comsol. (i. I'm using the Comsol 5. Right-click the Heat Transfer in Solids node (for example), and choose Pointwise Constraint from the Points submenu. This definition of the variance is valid for fixed population of values. Unlike the Classic constraints, these constraints do not enforce the temperature on the boundary extremities. In many cases, materials supplied yes you can define the heat flux as the function of temperature as a variable and use it as a boundary condition at the location you want to set. This type of coupling is one example of the manual approach with user-defined couplings. Table 3-1: Heat Transfer Predefined Variables. Posted 14 ott 2021, 09:04 GMT-7 Heat Transfer & Phase Change, Equation-Based Modeling 0 Replies . Dew Point Temperature. This adds a Lagrange multiplier for Some features define a local temperature: ht. The expression can include derivatives with respect to space and time or any other derived value. Derived variables may be the components of the heat flux vector, which are defined using the temperature variable. One specific example is as follows. In this model the COMSOL variable ht. T - Global scope Failed to evaluate variable. After thermal expansion, the size is L x a x b. For example, when a boundary heat source is applied on a particular side of the layer, this local variable ht. 0, where a coupling variable, similar to the Integration Coupling Variable present in the current release, can be defined that returns the *maximum* value instead of the *integrated* value. Contact; you may know that the actual electric potential can get up to 10 kV Response from COMSOL support: This is unfortunatley not possible in the current release. We are using a volumetric heat I have used COMSOL I am trying to plot the average temperature of a specific object in my geometry over time. 2 included many composed modules "pre-cooked". T, where < phys> is the tag of the physics interface. but it is changing its not a single value like when i open a door to put the sample it increases say to -10 and then later it goes -20, -30 until it stabilizes say to -35. Tempref, which is set by default to 293. feat1. T, where <phys> is the tag of the physics interface. And power is provided into it and the temperature distribution is monitored. When using the Heat Transfer Module, the Moist Air option in the Fluid Settings As an example, you can access the variable named tflux using ht. psat is used without explanation. i computed successfully using function that case has only variables of temperature. I am new to COMSOL, and i am trying to model of ac losses in HTS cable. Temperature distribution after 3 hours (left); relative humidity distribution after 3 hours (center); and the evolution of the condensation indicator variable, ht. In the solid mechanic module (solid) I use, I cannot find any dependent temperature variable or I'm not able to identify it. In order to understand how this works, enable the Equation View, and look at the implementation of the Dirichlet condition (in this case, a prescribed temperature):. But i dont get it yet how to define ambient temperature variant to my simulation. I case anyone comes across this post looking for the interal time-step size variable in comsol: The 'timestep' variable appears to be defined only during solution but not stored. Posted Nov 18, 2019, 4:06 p. - Variable: minput. Tempref, which is set to 293. bhs1. PDT Computational Fluid Dynamics (CFD), Heat Transfer, If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help. phi. Then in the place where you specify your temperature (whether it is a boundary condition or domain condition) you insert foo(t), t being COMSOL's exclusive variable name for time. Similarly, the Down indicator variable will go smoothly from negative to positive at 45°C. a temperature T) the value of a dependent variable at a given point (by analogy edge, boundary or domain) you define a My_T = intop1(T) where intop is an integration coupling operator define ON THE POINT (or an aveop1(), average operator defined on the edge, boundary or domain respectively) Now is the question: How can I set up a maximum temperature for my material? Thanks in advance! Carl. Ke. Using Global Equations to Solve the Model. but i think, it is not exactly result because conductivity function is consisted of temperature and electrci field. So Comsol shall calculate for each time step the variable with the current temperature. You can find more information in a previous blog post on modeling convective heat transfer. I am currently on a problem where I have a Temperature dependent heat source, in my formula I put the temperature as "T" variable. ) In the Study Settings window, in the section called Results While Solving , we change from the Output from solver option (which would just give us the results at t=0 and t=10[h]) to Some of these sections may be empty, specifically if none of the properties given in that node has a temperature dependence. Conditional Statement with Temperature and time variables. e. It seems that the global ODE node does not recognize the default model input temperature minput. This can be done either by explicitly giving a temperature or by selecting a temperature variable from another physics interface. COMSOL Multiphysics will take care of T_s^{-1}(T_d(x_d,y_d)), a necessary step in identifying the source coordinates. Then solve it numerically with Comsol and compare the results. Wish this helps Lasse Without seeing your model I suggest the following: I guess you have two physics modules, heat transfer in solids and heat transfer in fluids. Defining a component coupling operator and a variable. Posted May 5, 2014, 5:11 p. Analytic functions are used to specify material properties as functions of one or more arguments or as independent variables, such as temperature or pressure. However, the expression is marked red which means that there is an error, which I could not define. The heat transfer equations are solved for the temperature, while the heat flux components may be used to formulate these equations or to generate streamline and arrow plots when the How to enter the temperature that varies with time?? Posted Feb 3, 2013, 10:02 p. I would like to make a graph of temperature in a specific location as a function of time. mu. The available options are User defined (default), Common model input (the minput. Posted May 12, 2019, 2:12 a. Nichal Gentilal. The pressure, velocity, and temperature variables of the Nonisothermal Flow coupling node are set to the Common Model Input values of the Default Model Inputs node on its complementary selection, See Default Model Inputs in the COMSOL Multiphysics Reference With the release of version 5. In COMSOL Multiphysics ®, if you are simulating several components in a system, or a complete model that has submodels, you can manually couple the physics in different model components when needed. The first thing I would do would be to separate this table into two tables with only two columns for each table - independent variable (temperature) and dependent variable (ie, They appear in the Model Inputs section if a material is defined so that a material property becomes a function of the temperature, for example. The Equation View for the Temperature node. Does have anybody an idea how to realize this in comsol? My status: beginner Thanks a lot For example, defining a heat source based on an integration operator over the whole domain that is also a function of temperature (the dependent variable) leads to a coupling between all the degrees of freedom in the model creating a There are also more advanced types of flux conditions, where the flux or force is calculated based on local values of dependent variables and other parameters. 15. I am new to Comsol, My question is how to set and environment temperature in comsol heat transfer module. Then you label the function as rho, for example, and you call it with rho(T) in your governing equations. Hi you can replace your XXX with something like T0[K]+DT[K/s]*t where T0 is a constant scalar representing the initial temperature in Kelvin, and DT is the temperature increase with time (the numbers and units are typically which goes smoothly from negative to positive as the sensor temperature rises above 55°C. Note that the source map needs to be one-to-one for the inverse to exist. Today, we have introduced an approach appropriate for modeling materials exhibiting thermal hysteresis under the assumption of constant density and that the material must go completely above and below the melting and freezing temperatures to change phase. T variable, click the Go to Source button ( ), and in the Default Model Inputs node under Global Definitions , set a value for the Temperature in the Expression for remaining selection I also want to get a point-by-point value for the boundary condition so I would not prefer integrating/averaging the temperature over each boundary. In this assumption, the comsol can work well. If the former has the temperature variable T1 and the latter T2, set in the former module temperature to T2 on the boundary, and in the latter T1. The Information section also shows the deduced unit for the controller, which should match the unit of the acting quantity in the model (for example, m/s for a velocity or W for a heat source). | 7 defines buoyancy forces induced by density differences, in particular due to temperature dependency of the density. Enabling the Equation View. It is called with the two integration limits being the reference temperature <phys>. Next, to modify the emissivity to be a function of temperature, the simplest approach is to enter an expression with respect to the temperature variable, as shown in the screenshot below. Variables can also depend on dependent variables (the solution) and their derivatives, and they can have units. The Field node name matches the name of the variable. To alter the heating or cooling of a part based on the solution, you can add a temperature controller in your COMSOL model with a component coupling. Amin, To define the boundary heat source Q b as a function of the temperature, use the local temperature variable on the selected boundary, ht. Undefined variable. The unit of the sensitivity is the unit of the objective function divided by the unit of the control variable field, so in this case it is just radians (because the control variable field is dimensionless). nteflux, across all of the Use this subnode to specify the temperature on a set of lines (geometrical edges in 3D or geometrical points in 2D and 2D axisymmetric) that represent the boundaries of a thin domain (layer, film, fracture, or shell). Select an option from the External temperature list— User defined, or Temperature (ht/ht), the latter representing a temperature field calculated by a surrounding 3D solid physics. Use it somewhere in your model as aveop1(T) for the average temperature on that boundary. Posted Jan 7, 2019, 1:47 p. We will want to trigger a change in If you call in several physics with the same dependent variables, COMSOL calles them i. 0 10 Replies. Let’s take a look at the Global Equation interface, which gives us a list of variable names to enter — we’ll use Tair — and the equation to satisfy. To edit the Temperature field, click Make All Model Inputs Editable (). For example, a variable can be defined as pi*(R_tube^2-r_tube^2), where R_tube and r_tube are two other variables or parameters (for A dependent variable may be, for example, the temperature variable. Time dependant temperature at the boundary. Tref and the current temperature < phys>. It will generate an operator with a name like aveop1. Levent . 2) there is nowhere to excit the heat flux, if your liquid is flowing towards X then it takes with it part of the heat with the fluid mass flow, you need to define a HT outflow To edit the Temperature field, click Make All Model Inputs Editable (). 03. For User defined enter a value or expression for the temperature (the default is 293. Part 2 of a math-focused blog (temperature) on a surface; Weak contribution Global Equations node This node does not allow the creation of auxiliary variables, as opposed to weak contributions on explicitly defined Learn how to set up and solve electromagnetic heating problems in COMSOL Multiphysics® that involve high-frequency loads. Geometric Entity level. T variable, set to 293. A dependent variable may be, for example, the temperature variable. Tvar. where X is the variable for which you want to compute the variance (and the mean), x_i are the set of values that it takes, and \mu is the mean. In the Settings window, keep the default value for the temperature, 293. - The variable var1 is defined as a global variable, where T is not recognized as the variable for temperature because it is defined as a temperature field in the geometry in Model 1. And i want to observe the change of block's temperature. As an example, in Laminar Flow physics, the fluid density can often be found as The electric potential V is controlled such as the maximum temperature is below 100ºC. Radiation is the third mechanism for heat transfer that is included in the module. The State Variable feature simplifies the tracking of the history of a field over time. My problem is that once the variable reaches a local maximum temperature, I would like to be able to constrain the variable so it maintains that value until a new max temp is reached. So Comsol shall calculate for each time step the variable with You can specify a harmonic variation of the temperature value in a frequency domain analysis of perturbation type, by adding a Harmonic Perturbation subnode. 15 K by default) and all temperature variables from the physics interfaces included in the model. Send Private Message Flag post as spam. Best regards, For example, the Compute particle mass and Compute particle temperature check boxes in the settings window for The Particle Tracing for Fluid Flow Interface create auxiliary dependent variables for the particle mass and temperature, respectively. m. T_eq. The associated features handle surface-to-ambient radiation, surface-to-surface I had the same problem-temperature dependent structural and thermal properties. 15 K. (default), Common model input (the minput. To get the maximum temperature, you will want to take the maximum of the temperature at the previous time step and the temperature at the current time step, so you can introduce a variable in the model: MaxTemp = max(T,u) This will return the maximum temperature up to that time as shown in the plot below. Then, enter the arguments to the function and specify the Then integrate the ODE variable with a source term that is a Boolean variable that is 1 initially and becomes 0 when the temperature reaches a certain value (such as T_inpoint<400[K], where T_inpoint represents the temperature in that point. My question is, if it is possible to set the temperature in an area as a variable if the heat source is dependent on the temperature. Posted 18 mai 2011, 12:24 UTC−4 Parameters, Variables, variables". However, now i need to consider the effects of temperature on Jc and alpha. If you define the expression for the coefficient of thermal expansion yourself, you must ensure that it depends on a ‘free’ variable, and not use the same temperature variable as you use to prescribe the current To define the boundary heat source Q b as a function of the temperature, use the local temperature variable on the selected boundary, ht. Note: This discussion is about an older version of the COMSOL Multiphysics How to obtain values for a variable on the boundary? Posted Apr 19, 2011, 10:51 a. Many material properties, such as Young’s modulus, coefficient of thermal expansion, and yield stress, can have a significant dependence on temperature. In this blog post, we discuss how to automate this process in the COMSOL Multiphysics® software. This tutorial illustrates how to use built-in variables and operators, for the evaluation of the bulk temperature along a geometry like a channel, a pipe or a chimney, in a nonisothermal flow "Undefined" variable won't allow my study to execute. Variable. for completing my graduation. Variable Ambient Temperature . Of course it's possible in COMSOL to define material properties and global variables (these last ones by integration or similar operations) by the model temperature!! Please, be careful: you talk of Global variable: that's a variable independent on the position, that takes a unique value for all the geometry, and surely your IC variable is not such a variable. I mean, is it defined as the mean temperature inside my heated volume when it is used by my heat source ? In the above equations, T ambient is the temperature of the air surrounding the vacuum flask, and all other variables are defined in the function script, under step 6 in the section Modeling Instructions — MATLAB®. In COMSOL Multiphysics ®, you can see the underlying governing equations for the physics in a model, as well as the definitions of the variables. It was handed to me to fix, In one of the screenshots c Note: This discussion is about an older version of the COMSOL Multiphysics To start a new discussion with a link back to this one, click here. The methods are applicable to the dependent variables present as Field subnodes () under the Dependent Variables node. PST Chemical, Chemical Reaction Engineering, Parameters, Variables, but i don't know how to deal with a non-integer exponent in the unit of a variable. A 2D graph, with time on the x-axis and temperature (averaged) which would be something like aveop1(T), where aveop1 is the average operator and T is the temperature variable. 3a version. A good way to gain initial familiarity with COMSOL is to take advantage of the Model Library, which you can open under the File menu in Windows OS or under the Windows menu in Linux. 15 K). Click to expand the Constraint Settings section and select the Use weak constraints check box. One specific Hi everyone, I have a block in variable ambient temperature. The temperature is likewise represented in the model as a Here, the following variables have been introduced: I = Area moment of inertia around the bending axis; G = Shear modulus; K = Torsional modulus; J = Polar moment of inertia around the beam axis; It is assumed that the initial dimensions of the beam are L 0 x a 0 x b 0, where a 0 > b 0. Firstly, i have already implemented T-independent model, which assumes Jc and alpha as constant. Figure 3-8: The rate at which heat transfer occurs in both cases is governed by a temperature difference and a proportionality coefficient called the heat transfer coefficient. I would like to compute the temperature of the solid rectangle with temperature-dependent thermal conductivity and heat transfer coefficient at one of the boundaries. This is also what occurs when you use a variable (TC, for example) defined as 100[degC]. psat. Tvar, that corresponds to the appropriate variable (upside, downside, or average temperature of a layer, wall temperature with turbulence modeling), depending on the model configurations. The problem is, i can't find the way to vary the temperature. 15 K by default. T00 and an expression T for the temperature as defined on this boundary. I'm in necessary to designing a temperature sensor in COMSOL. Definition of temperature as a domain variable. If an expression is used for T ext that is a locally defined variable on the edge, the check box Take average in adjacent During the heating phase the temperature evelution in both materials is completely different. Equivalent Temperature. But i dont get it Dear All I have to apply temperature boundary condition which is varying from 10 deg to 40 deg in 90 min. 2018, 01:34 GMT-8 0 Replies . For example, Using it for Temperature in previous time step - prev(T,1) I got the answer that the previous time step is not stored. Send To use this as a boundary condition take not of the name that COMSOL gives to your operator, by default it is "maxop1". You can do that for other variables too, space for instance. Tref and the current temperature <phys>. I model a single channel and I am tracking fluid temperature and properties using variables. The problem remains even if I use a standard material like water. If you define the expression for the coefficient of thermal expansion yourself, you must ensure that it depends on a ‘free’ variable, and not use the same temperature variable as you use to prescribe the current Dear Comsol Community, I am looking for a way to find the location of the maximum of a variable. 3a, Version 4. Please login with (The time-stepping algorithm used by COMSOL ® for this simulation is a so-called variable-order BDF method that adapts its steps in time, based on the solution and the tolerance settings. In general you have to supply the temperature in all the Model Inputs sections. kkigy dht ioz aqbpbms bjmt qyjv ijmkfo fgmhrm qnxnp hdzl