Accessing y+ Cell Value within Fluent UDF

jackchilvers · July 22, 2014, 13:58

Dear all,

I am looking to gain access to cell y+ values within a Fluent UDF in order to prescribe a set value for my user-defined scalar for all cells where y+ < 100. Could you please advise a suitable macro?

Many thanks in advance.

yasinwind · January 29, 2018, 04:52

I am facing the same problem right now while trying to define a new turbulent viscosity (in the Buffer-Zone) depending on the dimensionless y+ value.
My aim is to to better take into account the change of the boundary profile along the wall with using the y+ value instead of the actual wall distance (in meters).

Maybe someone has found a solution or could share his advice.

edit: What I got so far is a definition with a function f(y) which I'd like to change to a function f(y+):

DEFINE_TURBULENT_VISCOSITY(XX,c,t)
{
..
real y = C_WALL_DIST(c,t);
mu_t_SST=f(y)
...
}

thedal · December 13, 2023, 08:36

Have you figured this out?

July 22, 2014, 13:58	Accessing y+ Cell Value within Fluent UDF	#1
jackchilvers New Member Jack Chilvers Join Date: Dec 2013 Location: St Neots, Cambridgeshire Posts: 12 Rep Power: 13	Dear all, I am looking to gain access to cell y+ values within a Fluent UDF in order to prescribe a set value for my user-defined scalar for all cells where y+ < 100. Could you please advise a suitable macro? Many thanks in advance. thedal likes this.

December 13, 2023, 08:36		#3
thedal Member Thamilmani M Join Date: Sep 2017 Location: IIT Bombay, Mumbai Posts: 52 Rep Power: 9	Have you figured this out? __________________ Always Thedal

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
udf problem	jane	Fluent UDF and Scheme Programming	37	February 20, 2018 05:17
DEFINE_DIFFUSIVITY udf in fluent	maniek940	Fluent UDF and Scheme Programming	2	August 13, 2013 18:13
Identifying cell in parallel UDF	upeksa	Fluent UDF and Scheme Programming	0	July 24, 2013 12:27
UDF problem caused by various version of Fluent	Yurong	FLUENT	3	January 15, 2006 11:57
UDF of Zimont model in fluent	Z	Main CFD Forum	0	February 17, 2005 04:07

January 29, 2018, 04:52		#2
yasinwind New Member Join Date: Nov 2017 Posts: 1 Rep Power: 0	I am facing the same problem right now while trying to define a new turbulent viscosity (in the Buffer-Zone) depending on the dimensionless y+ value. My aim is to to better take into account the change of the boundary profile along the wall with using the y+ value instead of the actual wall distance (in meters). Maybe someone has found a solution or could share his advice. edit: What I got so far is a definition with a function f(y) which I'd like to change to a function f(y+): DEFINE_TURBULENT_VISCOSITY(XX,c,t) { .. real y = C_WALL_DIST(c,t); mu_t_SST=f(y) ... }