CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   Siemens (https://www.cfd-online.com/Forums/siemens/)
-   -   Pseudo Transient approach (https://www.cfd-online.com/Forums/siemens/54348-pseudo-transient-approach.html)

 Xobile January 28, 2005 03:09

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 18:34

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 29, 2005 00:41

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 04:13

Re: Pseudo Transient approach

try reducing residual tolerance for primary variables to avoid this problem

 Piet January 29, 2005 15:39

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 06:03

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

 itsme_kit June 30, 2014 05:19

Quote:
 Originally Posted by Far (Post 428462) Transient simulation is to solve the problem in time-accurate fashion, while pseudo transient is method to get the steady state solution
Hi

In what problems, we are recommended to apply pseudo transient method?

Thanks

[QUOTE=itsme_kit;499259]Hi

In what problems, we are recommended to apply pseudo transient method?

Could someone having experience with pseudo transient method kindly comment when or in which cases does one implement in the soution methods in fluent

 LuckyTran February 19, 2018 16:38