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Xobile January 28, 2005 02:09

Pseudo Transient approach
 
Hello,

does anyone have any tutorial or simulation which uses pseudo transient approach as an initial guess for flow field initialization?

I am running a high speed compressible flow and would really appreciate any help,

Piet January 28, 2005 17:34

Re: Pseudo Transient approach
 
A tutorial what for? Just switch it on, set your time step (in your case 1.E-08) and run it! There's nothing special that could be mentioned in a tutorial!!!

hope this helps

Piet

Xobile January 28, 2005 23:41

Re: Pseudo Transient approach
 
when i am running steady state option for high speed compressible flow... it is giving me a converged solution.

But when i run the same case for pseudo-transient case, the simulation stops due to negative densities in more than 100 cells.. of course my time step was 0.1

will decreasing my time step to 1E-8 solve this issue??


sankar January 29, 2005 03:13

Re: Pseudo Transient approach
 
try reducing residual tolerance for primary variables to avoid this problem

Piet January 29, 2005 14:39

Re: Pseudo Transient approach
 
Yes, your are absolutely right. It can solve your problem. Maybe 1.E-8 is not small enough! Try to lower it further for several hundred steps and enhance it from time to time. Any hint for such cases is to start the calculation with a dependency of temperature. This means rho = f(T) and switch back after lets say 100 iterations.

best regards

Piet

crispysalt February 3, 2013 05:03

What is the difference between pseudo transient simulation and transient simulation?

Far May 18, 2013 14:22

Transient simulation is to solve the problem in time-accurate fashion, while pseudo transient is method to get the steady state solution


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