CFD Online Discussion Forums

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   CFX (https://www.cfd-online.com/Forums/cfx/)
-   -   Changing from explicit to implicit ???? (https://www.cfd-online.com/Forums/cfx/144401-changing-explicit-implicit.html)

ReCr November 13, 2014 12:02

Changing from explicit to implicit ????
 
My professor keeps asking us to go through the tutorials and run the same trial but switch from implicit to explicit to see how the results vary. But everything I have read online and in the user guide suggest this can't be done...I'm i right or is my professor?

ghorrocks November 13, 2014 17:20

Switch between implicit and explicit for what? There are many different parts of the CFD solver and some are implicit and some are explicit. But if you mean the main pressure-momentum coupling equations (ie the Navier Stokes solver) then CFX is an implicit solver and has no explicit option.

ReCr November 13, 2014 17:57

I'm assuming that he meant for solving the NS equations. The only other way to change between explicit and implicit would be for the turbulence, Correct?

ghorrocks November 13, 2014 20:01

No, turbulence is implicitly included in the solution. It is solved in a separate matrix so it is loosely coupled with the NS equations but still is implicit.

I think I got my wires crossed there. Fluent allows selection of several implicit or explicit options, including for the NS equations and for several multiphase models as well. I do not think CFX has an explicit option of any model that comes to mind.

sircorp June 8, 2015 08:16

Quote:

Originally Posted by ghorrocks (Post 519093)
No, turbulence is implicitly included in the solution. It is solved in a separate matrix so it is loosely coupled with the NS equations but still is implicit.

I think I got my wires crossed there. Fluent allows selection of several implicit or explicit options, including for the NS equations and for several multiphase models as well. I do not think CFX has an explicit option of any model that comes to mind.

Interesting : (Only for Fluent Users : I am not an expert, just tying to find quicker way to solve Density Based Implicit Method in Fluent).

Question is ? Can I stop half way through an implicit method and switch to explicit method ? Will it save time ? (assuming I use current value from implicit method in explicit method ) ?

Shane

ghorrocks June 8, 2015 19:44

No idea. Try asking on the Fluent forum.


All times are GMT -4. The time now is 07:45.