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Using stationary computational results as the initial condition for time-dependant solution
Posted Feb 8, 2012, 1:40 p.m. EST Heat Transfer & Phase Change, Studies & Solvers Version 4.2 5 Replies
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Is it possible to use the reults of a stationary study as the initial conditions for transient analysis?
For example, in my current model(using the joule heating and optimization module), I have system heating up to a steady state temperature through a defined current density and boundary heat source. I want to know how long it will take for all parts of the system to cool down to room temperature if the heater and current are turned off.
So far, I've tried introduce a stationary solver as step one, and then a time-dependant solver as step two. However, this just gives me a time dependant solution of the system heating up (not cooling down). I have also tried to use the "Store Solution 2" option in the solver configurations by
- right clicking on the "Store Solution" option and selecting "compute to selected"
- manually changing the heat source and current density to 0
- deleting the optimization solver
- selecting "use store solution 2" under solver configurations--> dependant variables 2 --> Initial values of variables solved for
- and finally right clicking on the "Store Solution" option and selecting "compute from selected"
But, this method just gave me a solution of everything at room temperature.
Can you please help me with this problem?
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this does work, so you must have missed a link somewhere. In 4.2a (and normally it worked also well before) if you add two solvers stationara + time series, and in thet order, when you define your physics, COMSOL will automatically link the two ,y saving the results of the stationary into a stored solution, and in the dependent variables node of the time series, it will link to the stored solution for the initial parameters.
remains what to do with variables not defined in the stationary case (if exist) ther too there are different options, to use "0" or the intial values or results from elsewhere. Now I'm not sure exactly how it will be for your case.
The best is to study the examples in the model library, I agree, not trivial to find a model with two steps easily in the large number of model therein, but try a search
--
Good luck
Ivar
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Is the stationary means the steady state condition? If the answer is yes, why COMSOL asks for initial condition?
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In some types of analyses initial values must be provided:
• As the initial condition for a time-dependent analysis.
• As an initial guess for the nonlinear stationary solver.
• As a linearization (equilibrium) point when solving a linearized stationary model or when performing an
eigenvalue study."
Best,
Jeff
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