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Step 1 results as initial values for step 2?

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I have the following problem:

A study with two time dependent steps:
step 1: the hydrostatic Navier-Stokes equation is solved for pressure variable p0
step 2: the full Navier-Stokes equation is solved for variables u,v,w,p. How do I initialize the pressure field p with p0?

i.e. I have defined two distinct equations in variables p0 and u,v,w,p respectively.

If I try the following for 'Dependent Variables 2' of step 2, COMSOL still calculates its own (incorrect) initial values at the beginning of step 2.

img40.imageshack.us/img40/5387/dependentvariables.png

Btw, 'Step 1 saved' solution is a save solution object that stores the solution of step 1. In the 'Initial values' object of the full NS equation, I have put p=p0 as initial value.

Any help would be greatly appreciated!

3 Replies Last Post 2014年7月3日 GMT-4 04:28

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Posted: 1 decade ago 2012年2月10日 GMT-5 04:58

I have the following problem:

A study with two time dependent steps:
step 1: the hydrostatic Navier-Stokes equation is solved for pressure variable p0
step 2: the full Navier-Stokes equation is solved for variables u,v,w,p. How do I initialize the pressure field p with p0?

i.e. I have defined two distinct equations in variables p0 and u,v,w,p respectively.

If I try the following for 'Dependent Variables 2' of step 2, COMSOL still calculates its own (incorrect) initial values at the beginning of step 2.

img40.imageshack.us/img40/5387/dependentvariables.png

Btw, 'Step 1 saved' solution is a save solution object that stores the solution of step 1. In the 'Initial values' object of the full NS equation, I have put p=p0 as initial value.

Any help would be greatly appreciated!


solve step :! . Then,
go to solvers, right click and select solution ---> copy
Use step 2 and say initial values from "copy2" whatever you have named ... from initial values node you can do this .. !
[QUOTE] I have the following problem: A study with two time dependent steps: step 1: the hydrostatic Navier-Stokes equation is solved for pressure variable p0 step 2: the full Navier-Stokes equation is solved for variables u,v,w,p. How do I initialize the pressure field p with p0? i.e. I have defined two distinct equations in variables p0 and u,v,w,p respectively. If I try the following for 'Dependent Variables 2' of step 2, COMSOL still calculates its own (incorrect) initial values at the beginning of step 2. http://img40.imageshack.us/img40/5387/dependentvariables.png Btw, 'Step 1 saved' solution is a save solution object that stores the solution of step 1. In the 'Initial values' object of the full NS equation, I have put p=p0 as initial value. Any help would be greatly appreciated! [/QUOTE] solve step :! . Then, go to solvers, right click and select solution ---> copy Use step 2 and say initial values from "copy2" whatever you have named ... from initial values node you can do this .. !

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Posted: 1 decade ago 2012年2月13日 GMT-5 07:53
Thanks for your suggestion, it works.

Since I want to use this in a parametric sweep, I'd guess that I will probably be best off by implementing this in a comsol/matlab script.
Thanks for your suggestion, it works. Since I want to use this in a parametric sweep, I'd guess that I will probably be best off by implementing this in a comsol/matlab script.

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Posted: 1 decade ago 2014年7月3日 GMT-4 04:28
I have the same problem, but I don't understand this answer.
Anyone could explain it in more details?
I have the same problem, but I don't understand this answer. Anyone could explain it in more details?

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