Simple algorithm

Bisht · March 14, 2016, 05:26

Hi, I would like to know that is this simple algorithm flow chart is correct?

mprinkey · March 14, 2016, 09:35

No, it isn't. The process of solving the pressure equation and adjusting the velocity field will enforce the mass conservation equation (to within the solution accuracy of the pressure solution). The test for the next iteration is whether or not the momentum (and other field) equations have converged. See here:

https://en.wikipedia.org/wiki/Soluti...n_steady_flows

Bisht · March 14, 2016, 10:34

Do you mean that in place of continuity equation satisfied, it would be solve all other discretised equation? rest of the algorithm is okay?

P.S. Simple algorithm for the transient simulation

mprinkey · March 15, 2016, 04:05

There is no difference between SIMPLE transient and steady-state. SIMPLE without d/dt terms converges to the steady state solution (if it converges). SIMPLE with implicit d/dt terms converges to the solution at the next timestep (if it converges). If you take a transient SIMPLE code and choose and very large dt, it will effectively become steady-state SIMPLE.

The link that I posted has a nice description of the SIMPLE algorithm--it is specifically for steady solutions, but, as I said, it doesn't matter whether SIMPLE is converging to the answer at t=t0 + dt or as t -> infinity.

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March 14, 2016, 09:35		#2
mprinkey Senior Member Michael Prinkey Join Date: Mar 2009 Location: Pittsburgh PA Posts: 363 Rep Power: 25	No, it isn't. The process of solving the pressure equation and adjusting the velocity field will enforce the mass conservation equation (to within the solution accuracy of the pressure solution). The test for the next iteration is whether or not the momentum (and other field) equations have converged. See here: https://en.wikipedia.org/wiki/Soluti...n_steady_flows

March 14, 2016, 10:34		#3
Bisht Member Kamal Bisht Join Date: Jun 2015 Location: Germany Posts: 57 Rep Power: 10	Do you mean that in place of continuity equation satisfied, it would be solve all other discretised equation? rest of the algorithm is okay? P.S. Simple algorithm for the transient simulation

March 15, 2016, 04:05		#4
mprinkey Senior Member Michael Prinkey Join Date: Mar 2009 Location: Pittsburgh PA Posts: 363 Rep Power: 25	There is no difference between SIMPLE transient and steady-state. SIMPLE without d/dt terms converges to the steady state solution (if it converges). SIMPLE with implicit d/dt terms converges to the solution at the next timestep (if it converges). If you take a transient SIMPLE code and choose and very large dt, it will effectively become steady-state SIMPLE. The link that I posted has a nice description of the SIMPLE algorithm--it is specifically for steady solutions, but, as I said, it doesn't matter whether SIMPLE is converging to the answer at t=t0 + dt or as t -> infinity.