[Jurado]

Hello people,

Is there a reason why you do not use the "nutkAtmRoughWallFunction" that uses directly z0 ?

[mAlletto]

Can you provide a better description of your test case. Domain, inital and boundary conditions.

[Jurado]

Originally Posted by mAlletto

Can you provide a better description of your test case. Domain, inital and boundary conditions.

My question was just about the boundary condition on the ground for atmospheric boundary condition. Because I saw a lot of people using the sand grain relationship with ks and cs and that they had to convert their roughness length z0 into ks and cs.


While for I there is no need for that in as much as there is already a boundary condition for nut that take directly z0 parameter.

So I was wondering if something was wrong with it for people not using it or if people just didn't know it existed.

[Shuveksha]

How do you put that value or program for roughness in ansys?
The roughness that is inbuilt in cfd is which kind of roughness?

[MMRC]

Originally Posted by Jurado

My question was just about the boundary condition on the ground for atmospheric boundary condition. Because I saw a lot of people using the sand grain relationship with ks and cs and that they had to convert their roughness length z0 into ks and cs.


While for I there is no need for that in as much as there is already a boundary condition for nut that take directly z0 parameter.

So I was wondering if something was wrong with it for people not using it or if people just didn't know it existed.

Hi Jurado,

I know its been years since your post. I'm somehow new to this ABL set-up, and I will rely on using atmNutWallFunc + omega/Epsilon atmEallFunc since they consider z0. I've seen too some foamers that uses standard wall BC's but there is a need (a must) to set z0 because this will help up to displace our wall level so we can mesh with y+ >> 30 & >> 300.

I do have an issue that pressure gradient running steady simpleFoam gaves me negative pressure at the inlet and 0 at outlet, using atmInlet BC's, but I think is because setting outlet to 0 and providing inlet velocity

Could you share the assumpation that you came to at that time?