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-   -   Coupled solver--> Implicit/explicit (http://www.cfd-online.com/Forums/star-ccm/112834-coupled-solver-implicit-explicit.html)

Sam0508 February 6, 2013 06:57

Coupled solver--> Implicit/explicit
 
Hello,

I) I would like to know how i can choose Either implicit unsteady or explicit unsteady while working in coupled solver.Is there any condition to choose?

II) When i sloved by unsteady state condition it take long time to slove simualtion. how i would minimize the iterating time.
and also what is relationship between CFL,Courant number,time step,No of inner iteration and Maximum physical time.will this five parameter will help to min time?

Plz any one can reply for this.

Rergards,
sam0508

Far March 24, 2013 02:31

Quote:

Originally Posted by Sam0508 (Post 406294)
Hello,

I) I would like to know how i can choose Either implicit unsteady or explicit unsteady while working in coupled solver.Is there any condition to choose?

II) When i sloved by unsteady state condition it take long time to slove simualtion. how i would minimize the iterating time.
and also what is relationship between CFL,Courant number,time step,No of inner iteration and Maximum physical time.will this five parameter will help to min time?

Plz any one can reply for this.

Rergards,
sam0508

For unsteady flow explicit formulation is good if time step is restricted (For example CFL<1) for some reasons.

Quote from Fluent training tut: (same should be true Star CCM+ I guess)

Quote:

The Coupled-Explicit solver should only be used for unsteady flows when the characteristic time scale of problem is on same order as that of the acoustics. e.g., tracking transient shock wave


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