SU2 2.0.8 stops with the option LINEAR_SOLVER=LU_SGS

taxalian · October 14, 2013, 16:20

I want to run the simulation by using the following parameter in config file with SU2 2.0.8 release:

LINEAR_SOLVER= LU_SGS, the code stop immediately by giving the following error:

ERROR: Cannot find value LU_SGS in given map.
Please check the name of the variable in the config file.

LINEAR_SOLVER= BCGSTAB, the code runs normally.

The question here is that is the LU_SGS option will not be available in the next regular release or its a bug in this developer release.

jentink · October 15, 2013, 08:10

LU_SGS does work for pre-conditioner option (LINEAR_SOLVER_PREC)

copeland · October 15, 2013, 16:34

Hi Taxalian,

SU2 now uses Krylov subspace methods to solve the sparse linear system in SU2_CFD. As Tom said, you can still use LU_SGS as a pre-conditioner for the linear system.

Try:
LINEAR_SOLVER= FGMRES
-or-
LINEAR_SOLVER= BCGSTAB

These Krylov methods are powerful and have consistently shown better performance than LU_SGS for the developer test cases. At this time, there are no plans to re-implement LU_SGS as a primary linear solver within SU2.

Regards,
Sean

taxalian · October 15, 2013, 16:53

Thanks Tom and Copeland for your reply, i also figured it out about these options in the config_template file available with the SU2 2.0.8 release.

October 14, 2013, 16:20	SU2 2.0.8 stops with the option LINEAR_SOLVER=LU_SGS	#1
taxalian Senior Member Join Date: Nov 2010 Posts: 139 Rep Power: 15	I want to run the simulation by using the following parameter in config file with SU2 2.0.8 release: LINEAR_SOLVER= LU_SGS, the code stop immediately by giving the following error: ERROR: Cannot find value LU_SGS in given map. Please check the name of the variable in the config file. LINEAR_SOLVER= BCGSTAB, the code runs normally. The question here is that is the LU_SGS option will not be available in the next regular release or its a bug in this developer release.

October 15, 2013, 08:10		#2
jentink Member Tom Jentink Join Date: Jan 2013 Posts: 61 Rep Power: 13	LU_SGS does work for pre-conditioner option (LINEAR_SOLVER_PREC) taxalian likes this.

October 15, 2013, 16:34		#3
copeland Member Sean R. Copeland Join Date: Jan 2013 Posts: 40 Rep Power: 13	Hi Taxalian, SU2 now uses Krylov subspace methods to solve the sparse linear system in SU2_CFD. As Tom said, you can still use LU_SGS as a pre-conditioner for the linear system. Try: LINEAR_SOLVER= FGMRES -or- LINEAR_SOLVER= BCGSTAB These Krylov methods are powerful and have consistently shown better performance than LU_SGS for the developer test cases. At this time, there are no plans to re-implement LU_SGS as a primary linear solver within SU2. Regards, Sean taxalian likes this.

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October 15, 2013, 16:53		#4
taxalian Senior Member Join Date: Nov 2010 Posts: 139 Rep Power: 15	Thanks Tom and Copeland for your reply, i also figured it out about these options in the config_template file available with the SU2 2.0.8 release.