Infinite channel inlet

| programmer's documentation

- Main Page
- Related Pages
- Modules
- Data Structures
- Files

All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
Infinite channel inlet

# Local variables to be added

The following local variables need to be defined for the examples in this section:

integer ifac, iel, ii, ivar, irangv, iun, ilelt, nlelt
double precision xkent, xeent, xphi, xfb
integer ibc, ix, ny, ios
double precision uent, vent, went, xustar2, xdh, d2s3, rhomoy
double precision acc(2), fmprsc, fmul, uref2, vnrm
integer, allocatable, dimension(:) :: lstelt, mrkcel
double precision, dimension(:), pointer :: brom

# Initialization and finalization

Initialization and finalization is similar to that of the base examples

# Body

Here, we define an inlet boundary condition for a very long channel or duct with a section matching the boundary faces of group 'INLET'.

We fix a mean inlet velocity, and use a feedback loop assuming a fixed-point type behavior will allow us to reach a state matching that of a very long inlet channel.

Warning
  We assume other boundary conditions are defined before this one (ideally, using the GUI).
  We also assume that the mesh is orthogonal at the inlet, and we are using a RANS (not LES) computation. to the current inlet.

For EBRSM of V2f models, to avoid laminarization at the inlet, the initial velocity (at the first time step) is divided by 10 on inlet faces adjacent to the boundary, so as to ensure a velocity gradient and turbulent production. Otherwise, the initialization may fail.

call getfbr('INLET', nlelt, lstelt)
!==========
fmprsc = 1.d0 ! mean prescribed velocity
if (ntcabs.eq.1) then
! For the Rij-EBRSM model (and possibly V2f), we need a non-flat profile,
! so as to ensure turbulent production, and avoid laminarization;
! here, we simply divide the initial velocity by 10 for inlet
! faces adjacent to the wall.
! The loop below assumes wall conditions have been defined first
! (in the GUI, or in this file, before the current test).
if (iturb.eq.32 .or. itytur.eq.5) then
allocate(mrkcel(ncelet))
do iel = 1, ncelet
mrkcel(iel) = 0
enddo
do ifac = 1, nfabor
if (itypfb(ifac) .eq. iparoi) then
iel = ifabor(ifac)
mrkcel(iel) = 1
endif
enddo
endif
do ilelt = 1, nlelt
ifac = lstelt(ilelt)
iel = ifabor(ifac)
itypfb(ifac) = ientre
rcodcl(ifac,iu,1) = - fmprsc * surfbo(1,ifac) / surfbn(ifac)
rcodcl(ifac,iv,1) = - fmprsc * surfbo(2,ifac) / surfbn(ifac)
rcodcl(ifac,iw,1) = - fmprsc * surfbo(3,ifac) / surfbn(ifac)
if (iturb.eq.32 .or. itytur.eq.5) then
if (mrkcel(iel) .eq. 1) then
rcodcl(ifac,iu,1) = fmprsc/10.d0
endif
endif
uref2 = rcodcl(ifac,iu,1)**2 &
+ rcodcl(ifac,iv,1)**2 &
+ rcodcl(ifac,iw,1)**2
uref2 = max(uref2,1.d-12)
! Turbulence example computed using equations valid for a pipe.
! We will be careful to specify a hydraulic diameter adapted
! to the current inlet.
! We will also be careful if necessary to use a more precise
! formula for the dynamic viscosity use in the calculation of
! the Reynolds number (especially if it is variable, it may be
! useful to take the law from 'usphyv'. Here, we use by default
! the 'viscl0" value.
! Regarding the density, we have access to its value at boundary
! faces (romb) so this value is the one used here (specifically,
! it is consistent with the processing in 'usphyv', in case of
! variable density)
! Hydraulic diameter
xdh = 1.d0
! Calculation of friction velocity squared (ustar2)
! and of k and epsilon at the inlet (xkent and xeent) using
! standard laws for a circular pipe
! (their initialization is not needed here but is good practice).
rhomoy = brom(ifac)
xustar2 = 0.d0
xkent = epzero
xeent = epzero
call keendb &
!==========
( uref2, xdh, rhomoy, viscl0, cmu, xkappa, &
xustar2, xkent, xeent )
! itytur is a flag equal to iturb/10
if (itytur.eq.2) then
rcodcl(ifac,ik,1) = xkent
rcodcl(ifac,iep,1) = xeent
elseif (itytur.eq.3) then
rcodcl(ifac,ir11,1) = d2s3*xkent
rcodcl(ifac,ir22,1) = d2s3*xkent
rcodcl(ifac,ir33,1) = d2s3*xkent
rcodcl(ifac,ir12,1) = 0.d0
rcodcl(ifac,ir13,1) = 0.d0
rcodcl(ifac,ir23,1) = 0.d0
rcodcl(ifac,iep,1) = xeent
if (iturb.eq.32) then
rcodcl(ifac,ial,1) = 1.d0
endif
elseif (itytur.eq.5) then
rcodcl(ifac,ik,1) = xkent
rcodcl(ifac,iep,1) = xeent
rcodcl(ifac,iphi,1) = d2s3
if (iturb.eq.50) then
rcodcl(ifac,ifb,1) = 0.d0
elseif (iturb.eq.51) then
rcodcl(ifac,ial,1) = 0.d0
endif
elseif (iturb.eq.60) then
rcodcl(ifac,ik,1) = xkent
rcodcl(ifac,iomg,1) = xeent/cmu/xkent
elseif (iturb.eq.70) then
rcodcl(ifac,inusa,1) = cmu*xkent**2/xeent
endif
! Handle scalars
if (nscal.gt.0) then
do ii = 1, nscal
rcodcl(ifac,isca(ii),1) = 1.d0
enddo
endif
enddo
if (iturb.eq.32 .or. itytur.eq.5) then
deallocate(mrkcel)
endif
else
! Subsequent time steps
!----------------------
acc(1) = 0.d0
acc(2) = 0.d0
! Estimate multiplier
do ilelt = 1, nlelt
ifac = lstelt(ilelt)
iel = ifabor(ifac)
vnrm = sqrt(rtp(iel,iu)**2 + rtp(iel,iv)**2 + rtp(iel,iw)**2)
acc(1) = acc(1) + vnrm*surfbn(ifac)
acc(2) = acc(2) + surfbn(ifac)
enddo
if (irangp.ge.0) then
call parrsm(2, acc)
endif
fmul = fmprsc/(acc(1)/acc(2)) ! 1 / estimate flow multiplier
! Apply BC
do ilelt = 1, nlelt
ifac = lstelt(ilelt)
iel = ifabor(ifac)
itypfb(ifac) = ientre
vnrm = sqrt(rtp(iel,iu)**2 + rtp(iel,iv)**2 + rtp(iel,iw)**2)
rcodcl(ifac,iu,1) = - fmul * vnrm * surfbo(1,ifac) / surfbn(ifac)
rcodcl(ifac,iv,1) = - fmul * vnrm * surfbo(2,ifac) / surfbn(ifac)
rcodcl(ifac,iw,1) = - fmul * vnrm * surfbo(3,ifac) / surfbn(ifac)
if (itytur.eq.2) then
rcodcl(ifac,ik,1) = rtp(iel,ik)
rcodcl(ifac,iep,1) = rtp(iel,iep)
elseif (itytur.eq.3) then
rcodcl(ifac,ir11,1) = rtp(iel,ir11)
rcodcl(ifac,ir22,1) = rtp(iel,ir22)
rcodcl(ifac,ir33,1) = rtp(iel,ir33)
rcodcl(ifac,ir12,1) = rtp(iel,ir12)
rcodcl(ifac,ir13,1) = rtp(iel,ir13)
rcodcl(ifac,ir23,1) = rtp(iel,ir23)
rcodcl(ifac,iep,1) = rtp(iel,iep)
if (iturb.eq.32) then
rcodcl(ifac,ial,1) = rtp(iel,ial)
endif
elseif (itytur.eq.5) then
rcodcl(ifac,ik,1) = rtp(iel,ik)
rcodcl(ifac,iep,1) = rtp(iel,iep)
rcodcl(ifac,iphi,1) = rtp(iel,iphi)
if (iturb.eq.50) then
rcodcl(ifac,ifb,1) = rtp(iel,ifb)
elseif (iturb.eq.51) then
rcodcl(ifac,ial,1) = rtp(iel,ial)
endif
elseif (iturb.eq.60) then
rcodcl(ifac,ik,1) = rtp(iel,ik)
rcodcl(ifac,iomg,1) = rtp(iel,iomg)
elseif (iturb.eq.70) then
rcodcl(ifac,inusa,1) = rtp(iel,inusa)
endif
! Handle scalars (a correction similar to that of velocity is suggested
! rather than the simpler code below)
if (nscal.gt.0) then
do ii = 1, nscal
rcodcl(ifac,isca(ii),1) = rtp(iel,isca(ii))
enddo
endif
enddo
endif