Learning Forum

[Jason Sum]

NA

[Rob]

You may want to check your direction vector for "up". If z is up it's not [1] in the vector definition! 

[Jason Sum]

Hi Rob, thank you for the guide.

I have rotated my geometry so that y is pointing upwards to meet the UDF.

Still same errors occur during initialisation. Everything works when I just insert constant velocity for inlet without udf

Sincerely hoped for further advice, Thanks!

[Rob]

I'd have changed the UDF! What is the minimum y value in the domain? Use the Scale tool in Fluent to find out. 

[Jason Sum]

 

 

Yes I have altered the ZREF and LREF according to my building geometry with height (z-axis): 150m and cross-sectional width: 64.4m. For the rest of the UDF, I think they describing the general solving for atmospheric boundary layer in velocity, k and epsilon, so I didnt modify it. 

 

 

#include "udf.h"
#define UREF 4.491 // reference wind speed at ZREF
#define ZREF 150.0 // height of the building, 2b
#define LREF 64.4 // characteristic length, b
#define CMU 0.09 // 

 

Or are you referring to the mini. y+ of my mesh domain?

Thank you for help.

 

 

[Rob]

No, what is the minimum y coordinate on the inlet? 

Before going too much into y+ how confident are you about the ground position and detail? I see far too many thinking y+ is the only mesh metric, and if you have bushes, trees, curbs etc did you also resolve all of those?