Method for solving the adjoint equations

fumiya · June 12, 2011, 21:31

Hi,

I have run several cases and found it difficult to obtain a converged
solution of the adjoint N-S equations. I think it is related to the adjoint
transpose convection term. I use the SIMPLE algorithm to couple the
adjoint velocity and pressure.

What should I do to improve convergence of the adjoint equations?
Any information, however small, would be appreciated.

Best regards,
fumiya

Petrov · June 13, 2011, 00:18

First, check that you should get a solution that converges. For high Re, (even about 40 in some cases), you would get a time-dependent solution. To check that it works for low Re, increase the viscosity, decrease the velocity, etc. If this doesn't work, there is a problem.

I don't know much about the SIMPLE algorithm, but if it involves solving a system of equations, try using a pre-conditioner. Without a pre-conditioner, I was not able to get a good result quickly. I implemented the gauss-siedel conditioner and it works like a charm. (Though maybe I should use SSOR!)

Good luck!

June 12, 2011, 21:31	Method for solving the adjoint equations	#1
fumiya Senior Member Fumiya Nozaki Join Date: Jun 2010 Location: Yokohama, Japan Posts: 266 Blog Entries: 1 Rep Power: 18	Hi, I have run several cases and found it difficult to obtain a converged solution of the adjoint N-S equations. I think it is related to the adjoint transpose convection term. I use the SIMPLE algorithm to couple the adjoint velocity and pressure. What should I do to improve convergence of the adjoint equations? Any information, however small, would be appreciated. Best regards, fumiya

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Adjoint solver for flow problems	jelmer	OpenFOAM Running, Solving & CFD	11	March 12, 2017 06:52
Calculation of the Governing Equations	Mihail	CFX	7	September 7, 2014 06:27
CFD governing equations	m.gos	Main CFD Forum	0	April 30, 2011 14:21
A question about discrete adjoint method	Thomas	Main CFD Forum	3	August 9, 2006 12:37
What is Density-Based method?	C-H Kuo	Main CFD Forum	4	November 18, 1998 16:11

June 13, 2011, 00:18		#2
Petrov New Member Felipe Hernandez Join Date: Apr 2011 Posts: 13 Rep Power: 15	First, check that you should get a solution that converges. For high Re, (even about 40 in some cases), you would get a time-dependent solution. To check that it works for low Re, increase the viscosity, decrease the velocity, etc. If this doesn't work, there is a problem. I don't know much about the SIMPLE algorithm, but if it involves solving a system of equations, try using a pre-conditioner. Without a pre-conditioner, I was not able to get a good result quickly. I implemented the gauss-siedel conditioner and it works like a charm. (Though maybe I should use SSOR!) Good luck!