How to Reduce Wall Y-Plus

July 23, 2006, 10:13

Freinds I have solved a combustion problem using non premixed combustion model in Fluent. Am getting every thing correct but, getting a high value of wall y-plus,...

can any one tell me how to reduce wall Y-Plus,...

waiting for u'r reply,...

regards,.....

rams

July 24, 2006, 02:56

Go to Adapt - Yplus/Ystar panel... Turn on Refine option, select wall zones yoe wih to refine, set the min and max allowed values of Yplus, and click Adapt ...

July 25, 2006, 04:27

Hi!

The adapt option is ok, BUT: most of the time, it can only dubble or half the y+ values, because the position of the nodes can not be changed with that option. So changing of yplus means to add or remove a node, and the addition can only happend in the middle of a cell.

One hint: Use the smooth/swap option after adapting yplus, do some iterations until convergens, than do the yplus adaption again.

Much better is it, to build a grid with the right yplus from the beginning. Use sizing function and/or Boundary layer option in gambit.

To estimate yplus, have a look at: http://www.cfd-online.com/Forum/main...cgi?read=44320

Ralf

July 25, 2006, 04:36

I would build a grid imposing the yplus that I wanted, and then recalculating the cell size. As I know you need to estimate velocity of the adjacent flow, carachterist length of the problem, Cf and Ue.

July 23, 2006, 10:13	How to Reduce Wall Y-Plus	#1
rams Guest Posts: n/a	Freinds I have solved a combustion problem using non premixed combustion model in Fluent. Am getting every thing correct but, getting a high value of wall y-plus,... can any one tell me how to reduce wall Y-Plus,... waiting for u'r reply,... regards,..... rams

July 24, 2006, 02:56	Re: How to Reduce Wall Y-Plus	#2
Marina Guest Posts: n/a	Go to Adapt - Yplus/Ystar panel... Turn on Refine option, select wall zones yoe wih to refine, set the min and max allowed values of Yplus, and click Adapt ...

July 25, 2006, 04:27	Re: How to Reduce Wall Y-Plus	#3
Ralf Schmidt Guest Posts: n/a	Hi! The adapt option is ok, BUT: most of the time, it can only dubble or half the y+ values, because the position of the nodes can not be changed with that option. So changing of yplus means to add or remove a node, and the addition can only happend in the middle of a cell. One hint: Use the smooth/swap option after adapting yplus, do some iterations until convergens, than do the yplus adaption again. Much better is it, to build a grid with the right yplus from the beginning. Use sizing function and/or Boundary layer option in gambit. To estimate yplus, have a look at: http://www.cfd-online.com/Forum/main...cgi?read=44320 Ralf

July 25, 2006, 04:36	Re: How to Reduce Wall Y-Plus	#4
Albert Franco Guest Posts: n/a	I would build a grid imposing the yplus that I wanted, and then recalculating the cell size. As I know you need to estimate velocity of the adjacent flow, carachterist length of the problem, Cf and Ue.

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