Thermal wall function.
Posted: Tue Jun 14, 2016 6:05 pm
Hello, I was checking clptur.f90 when I saw this bit of code:
I don't understand two things (among many others 
):
- why would the Neumann b.c. use hint (which is defined a bit earlier directly from the turbulent viscosity) and not hflui coming from the evaluation of the wall function?
- is there a particular advantage in using the Arpaci Larsen wall function when the turbulent diffusivity is known? I mean, following the theory guide, the Arpaci Larsen wall function is used to evaluate the term:
but if nu_t and sigma_t are known, K is known as well. Does this imply that using the wall function is an improvement of the linear eddy viscosity model for scalar diffusion? Do you know in which cases using icodcl(ifac,ivar)=5 gives better results than icodcl(ifac,ivar)=1?
Thanks
Jacopo
Code: Select all
! Dirichlet on the scalar, with wall function
if (iturb.ne.0.and.icodcl(ifac,ivar).eq.5) then
call hturbp(iwalfs,prdtl,sigmas(iscal),yplus,dplus,hflui,ypth)
! Compute (y+-d+)/T+ *PrT
yptp = hflui/prdtl
! Compute lambda/y * (y+-d+)/T+
hflui = rkl/distbf *hflui
! Neumann on the scalar, with wall function (for post-processing)
elseif (iturb.ne.0.and.icodcl(ifac,ivar).eq.3) then
call hturbp(iwalfs,prdtl,sigmas(iscal),yplus,dplus,hflui,ypth)
! y+/T+ *PrT
yptp = hflui/prdtl
hflui = hint
else
! y+/T+ *PrT
yptp = 1.d0/prdtl
hflui = hint
endif
- why would the Neumann b.c. use hint (which is defined a bit earlier directly from the turbulent viscosity) and not hflui coming from the evaluation of the wall function?
- is there a particular advantage in using the Arpaci Larsen wall function when the turbulent diffusivity is known? I mean, following the theory guide, the Arpaci Larsen wall function is used to evaluate the term:
but if nu_t and sigma_t are known, K is known as well. Does this imply that using the wall function is an improvement of the linear eddy viscosity model for scalar diffusion? Do you know in which cases using icodcl(ifac,ivar)=5 gives better results than icodcl(ifac,ivar)=1?
Thanks
Jacopo