Gradient Schemes

srv537 · January 11, 2017, 10:05

Hi

i just started using OpenFoam and i am comparing Fluent and OpenFoam result.

i have modified icoFoam (added energy equation) and trying to validate a paper result, they used Green-Gauss Node-Based method for gradient.

Fluent has three option for gradient scheme (Green-Gauss Cell-Based, Green-Gauss Node-Based, Least Squares Cell-Based) and Green-Gauss Node-Based simulation gives more accurate result (nearly 5-10% more accurate as compare to Green-Gauss Cell based and Least Squares Cell based).

in OpenFoam for gradient schemes we have
Gauss linear
cellLimited
cellMDLimited
edgeCellsLeastSquares
faceLimited
faceMDLimited
fourthGauss
cellLimited
cellMDLimited
edgeCellsLeastSquares
faceLimited
faceMDLimited
fourth
leastSquares
pointCellsLeastSquares
leastSquares
pointCellsLeastSquares

i tried with Gauss linear and got 10% error as compare to Fluent (Green-Gauss Node-Based). please suggest me which gradient scheme should i use to produce more accurate result?
is there any alternate of Green-Gauss Node-Based gradient scheme in OpenFoam?

Thank you

srv537 · February 11, 2017, 07:27

here is the plot of average Nu based on all these three gradient scheme but local Nu variation is same in all Scheme.

cryabroad · August 7, 2018, 23:24

Have you tried leastSquares in OF? For my case, when using this option in Fluent the simulation runs smoothly but in OF there are divergence issues.

January 11, 2017, 10:05	Gradient Schemes	#1
srv537 Member Saurav Kumar Join Date: Jul 2016 Posts: 80 Rep Power: 9	Hi i just started using OpenFoam and i am comparing Fluent and OpenFoam result. i have modified icoFoam (added energy equation) and trying to validate a paper result, they used Green-Gauss Node-Based method for gradient. Fluent has three option for gradient scheme (Green-Gauss Cell-Based, Green-Gauss Node-Based, Least Squares Cell-Based) and Green-Gauss Node-Based simulation gives more accurate result (nearly 5-10% more accurate as compare to Green-Gauss Cell based and Least Squares Cell based). in OpenFoam for gradient schemes we have Gauss linear cellLimited cellMDLimited edgeCellsLeastSquares faceLimited faceMDLimited fourthGauss cellLimited cellMDLimited edgeCellsLeastSquares faceLimited faceMDLimited fourth leastSquares pointCellsLeastSquares leastSquares pointCellsLeastSquares i tried with Gauss linear and got 10% error as compare to Fluent (Green-Gauss Node-Based). please suggest me which gradient scheme should i use to produce more accurate result? is there any alternate of Green-Gauss Node-Based gradient scheme in OpenFoam? Thank you

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August 7, 2018, 23:24		#3
cryabroad Senior Member Ruiyan Chen Join Date: Jul 2016 Location: Hangzhou, China Posts: 162 Rep Power: 9	Have you tried leastSquares in OF? For my case, when using this option in Fluent the simulation runs smoothly but in OF there are divergence issues.