I am simulating a time-dependent problem with very different successive physics in COMSOL. but some of these physics don't start from the beginning of the simulation. How can I set the start time of each physics?
Yes. However, I should have used the term study instead of solver. It goes something like this:
Study 1 generates dataset 'sol1'. Study 2 uses the last time step of 'sol1' as the initial value for dataset 'sol2. Study 3 uses the last time step of 'sol2' as the initial value for dataset 'sol3'. And so on... This way you can chain an arbitrary number of studies and evolve the solution in time.
COMSOL lets you modify the physics tree for each study. In the study node, just check the 'Modify physics tree and variables for study step' box. You can enable and disable physics nodes and the sub-nodes in a physics node for each individual study. For example Study 1 can solve only the Heat Equation. Study 2 can solve both the Heat Equation and Laminar Flow Equations. Study 3 can solve only the Heat Equation. And so on...
You will probably need to use multiple solvers and initialize new solutions using the solution from the pervious solver.
I agree with Kimmo Korhonen. Multiple solvers would help to your system. In addition, you may define different time ranges for each solver as well, then this helps you to set start time for each physics.
Dear masoud
first make sure your software and user defined functions are healthy and salubrious
although it is a rare problem, some times in a case your equation has no driving force for start. as an example you may simulate a exothermic reaction which is temperature-dependent.in fact you have created a loop with no start point.in such cases you may poke your case like injecting a disturbance.regards
Dear Mehdi thanks. but what you said is not related.
thanks Kimmo Korhonen and Turkay Kondakci. I thought about it previously but wanted something better. So, I have to define two solvers in which one of them, initial values are solution of the other one?
Yes. However, I should have used the term study instead of solver. It goes something like this:
Study 1 generates dataset 'sol1'. Study 2 uses the last time step of 'sol1' as the initial value for dataset 'sol2. Study 3 uses the last time step of 'sol2' as the initial value for dataset 'sol3'. And so on... This way you can chain an arbitrary number of studies and evolve the solution in time.
COMSOL lets you modify the physics tree for each study. In the study node, just check the 'Modify physics tree and variables for study step' box. You can enable and disable physics nodes and the sub-nodes in a physics node for each individual study. For example Study 1 can solve only the Heat Equation. Study 2 can solve both the Heat Equation and Laminar Flow Equations. Study 3 can solve only the Heat Equation. And so on...
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