[zx-81]

This is a follow up to a branch of another thread (i thought to open a new thread in order to not 'hijack' th other thread that originally had another topic)

In that thread we discussed Approximate Projection Methods (APM) and FMDenaro wrote:

Originally Posted by FMDenaro

Thus, I developed an exact double-projection method that works on non-staggered grid. I had good and oscillation-free solutions without adding dissipation. F

This double-projection method sounds very interesting indeed.

I have one question: Am I correct to assume that for the second elliptic solve of the "double projection" one can get away with significantly fewer iterations of the linear solver to reach the error tolerance ?

This would be important for the practicality of the method because typically already the first regular "single projection" solve takes most of the time of the whole simulation step.

But if it would be possible to solve the 'second stage' of your double projection method with, say, only a limited number of additional gauss-seidel/jacobi sweeps or Conjugate-Gradient iterations then this would be a very interesting option to consider to improve my non-staggered approximate pressure correction method.

[FMDenaro]

Originally Posted by zx-81

This is a follow up to a branch of another thread (i thought to open a new thread in order to not 'hijack' th other thread that originally had another topic)

In that thread we discussed Approximate Projection Methods (APM) and FMDenaro wrote:



This double-projection method sounds very interesting indeed.

I have one question: Am I correct to assume that for the second elliptic solve of the "double projection" one can get away with significantly fewer iterations of the linear solver to reach the error tolerance ?

This would be important for the practicality of the method because typically already the first regular "single projection" solve takes most of the time of the whole simulation step.

But if it would be possible to solve the 'second stage' of your double projection method with, say, only a limited number of additional gauss-seidel/jacobi sweeps or Conjugate-Gradient iterations then this would be a very interesting option to consider to improve my non-staggered approximate pressure correction method.

Yes, the second elliptic equation requires much less iteration to reach convergence, if you found my papers on IJNMF that is clarified ...
Of course, I used to start the iterations from the solution of the previous time step

[zx-81]

Originally Posted by FMDenaro

Yes, the second elliptic equation requires much less iteration to reach convergence, if you found my papers on IJNMF that is clarified ...
Of course, I used to start the iterations from the solution of the previous time step

Thanks a lot for the clarification !
I will try to digest the papers to better understand the details of the method.

[FMDenaro]

Ok, if you have questions you can ask for infos. The links of the two papers:

https://www.researchgate.net/publica...y-driven_flows

https://www.researchgate.net/publica...ids?ev=prf_pub

but I think that to understand better the theoretical basis of the DPM the details are here in this third paper
https://www.researchgate.net/publica...ary_conditions