Local variables to be added

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

integer          ifac, iel, ii, ivar
integer          izone
integer          ilelt, nlelt
double precision uref2, d2s3
double precision rhomoy, xdh, xustar2
double precision xitur
double precision xkent, xeent
 
integer, allocatable, dimension(:) :: lstelt
double precision, dimension(:), pointer :: boundary_roughness

Initialization and finalization

The following initialization block needs to be added for the following examples:

allocate(lstelt(nfabor))  ! temporary array for boundary faces selection
 
call field_get_val_s(ibrom, bfpro_rom)

Ad the end of the subroutine, it is recommended to deallocate the work array:

deallocate(lstelt) ! temporary array for boundary faces selection

In theory Fortran 95 deallocates locally-allocated arrays automatically, but deallocating arrays in a symmetric manner to their allocation is good practice, and it avoids using a different logic for C and Fortran.

Body

In the body, we may define several boundary conditions. Here are a few examples.

Inlet example with hydraulic diameter

Assign an inlet to boundary faces of group '2' and x < 0.01.

Warning: the <, <=, >, and >= operators may only be used with variables x, y, and z. This syntax is not a full equation interpreter, so formulas involving x, y, or z are not allowed.

Set a a Dirichlet value on the three components of $\vect{u}$ on the faces with the selection criterion '2 and x < 0.01' and set a Dirichlet to all the scalars $\varia$ .

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).

call getfbr('2 and x < 0.01', nlelt, lstelt)
 
 
do ilelt = 1, nlelt
 
  ifac = lstelt(ilelt)
  iel = ifabor(ifac)
 
  itypfb(ifac) = ientre
 
  rcodcl(ifac,iu,1) = 1.1d0
  rcodcl(ifac,iv,1) = 1.1d0
  rcodcl(ifac,iw,1) = 1.1d0
 
  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: to be defined in the notebook GUI
  xdh = notebook_parameter_value_by_name('hydraulic_diam')
 
  !   Calculation of turbulent inlet conditions using
  !     standard laws for a circular pipe
  !     (their initialization is not needed here but is good practice).
  rhomoy  = bfpro_rom(ifac)
 
  call turbulence_bc_inlet_hyd_diam(ifac, uref2, xdh, rhomoy, viscl0,  &
                                    rcodcl)
 
  ! Handle scalars
  if (nscal.gt.0) then
    do ii = 1, nscal
      rcodcl(ifac,isca(ii),1) = 1.d0
    enddo
  endif
 
enddo

Inlet example with turbulence intensity

Assign an inlet to boundary faces of group '3'.

Set a a Dirichlet value on the three components of $\vect{u}$ on the faces with the selection criterion '3' and set a Dirichlet to all the scalars $\varia$ .

Turbulence example computed using turbulence intensity data.

We will be careful to specify a hydraulic diameter adapted to the current inlet.

Calculation of and $\varepsilon$ at the inlet (xkent and xeent) using the turbulence intensity and standard laws for a circular pipe (their initialization is not needed here but is good practice)

call getfbr('3', nlelt, lstelt)
 
do ilelt = 1, nlelt
 
  ifac = lstelt(ilelt)
  iel  = ifabor(ifac)
 
  itypfb(ifac) = ientre
 
  rcodcl(ifac,iu,1) = 1.1d0
  rcodcl(ifac,iv,1) = 1.1d0
  rcodcl(ifac,iw,1) = 1.1d0
 
  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 turbulence intensity data.
 
  ! We will be careful to specify a hydraulic diameter adapted
  !   to the current inlet.
 
  ! Hydraulic diameter: to be defined in the notebook GUI
  xdh = notebook_parameter_value_by_name('hydraulic_diam')
 
  ! Turbulence intensity: to be defined in the notebook GUI
  xitur = notebook_parameter_value_by_name('turb_intensity')
 
  ! Calculation of turbulent inlet conditions using
  !   the turbulence intensity and standard laws for a circular pipe
  !   (their initialization is not needed here but is good practice)
 
  call turbulence_bc_inlet_turb_intensity(ifac, uref2, xitur, xdh,  &
                                          rcodcl)
 
  ! --- Handle scalars
  if (nscal.gt.0) then
    do ii = 1, nscal
      rcodcl(ifac,isca(ii),1) = 1.d0
    enddo
  endif
 
enddo

Assign an outlet to boundary faces of group 'outlet'

Outlet:

zero flux for velocity and temperature, prescribed pressure
Note that the pressure will be set to P0 at the first
free outlet face (isolib)

call getfbr('outlet', nlelt, lstelt)
 
do ilelt = 1, nlelt
 
  ifac = lstelt(ilelt)
 
  ! Outlet: zero flux for velocity and temperature, prescribed pressure
  !         Note that the pressure will be set to P0 at the first
  !         free outlet face (isolib)
 
  itypfb(ifac) = isolib
 
enddo

Wall example

Assign a wall to boundary faces of group '5'.

Wall:

zero flow (zero flux for pressure)
friction for velocities (+ turbulent variables)
zero flux for scalars

call getfbr('5', nlelt, lstelt)
 
do ilelt = 1, nlelt
 
  ifac = lstelt(ilelt)
 
  ! Wall: zero flow (zero flux for pressure)
  !       friction for velocities (+ turbulent variables)
  !       zero flux for scalars
 
  itypfb(ifac) = iparoi
 
  ! If sliding wall with velocity u = 1:
  ! rcodcl(ifac, iu, 1) = 1.d0
 
  ! If sliding wall with velocity u = 0: nothing to do
 
  if (nscal.gt.0) then
 
    ! If temperature prescribed to 20 with wall law (scalar ii=1):
    ii = 1
    icodcl(ifac, isca(ii))    = 5
    rcodcl(ifac, isca(ii), 1) = 20.d0
 
    ! If temperature prescribed to 50 with no wall law (simple Dirichlet)
    !   with exchange coefficient 8 (scalar ii=2):
    ii = 2
    icodcl(ifac, isca(ii))    = 1
    rcodcl(ifac, isca(ii),1)  = 50.d0
    rcodcl(ifac, isca(ii), 2) = 8.d0
 
    ! If flux prescribed to 4.d0 (scalar ii=3):
    ii = 3
    icodcl(ifac, isca(ii))    = 3
    rcodcl(ifac, isca(ii), 3) = 4.d0
 
  endif
enddo

Rough wall example

Assign a rough wall to boundary faces of group '7'.

Wall:

zero flow (zero flux for pressure)
rough friction for velocities (+ turbulent variables)
zero flux for scalars

call getfbr('7', nlelt, lstelt)
 
do ilelt = 1, nlelt
 
  ifac = lstelt(ilelt)
 
  ! Wall: zero flow (zero flux for pressure)
  !       rough friction for velocities (+ turbulent variables)
  !       zero flux for scalars
 
  itypfb(ifac) = iparug
 
  ! Roughness for velocity: 1cm
  rcodcl(ifac,iu,3) = 0.01d0
 
  ! Roughness for scalar (if required): 1cm
  rcodcl(ifac,iv,3) = 0.01d0
 
  ! If sliding wall with velocity u = 1:
  rcodcl(ifac, iu, 1) = 1.d0
 
  ! If sliding wall with velocity u = 0: nothing to do
  if (nscal.gt.0) then
 
    ! If temperature prescribed to 20 (scalar ii=1)
    ! (with thermal roughness specified in rcodcl(ifac,iv,3)) :
    ii = 1
    icodcl(ifac, isca(ii))    = 6
    rcodcl(ifac, isca(ii), 1) = 20.d0
 
    ! If flux prescribed to 4.d0 (scalar ii=3):
    ii = 3
    icodcl(ifac, isca(ii))    = 3
    rcodcl(ifac, isca(ii), 3) = 4.d0
 
  endif
 
enddo

Symmetry example

Assign a symmetry condition to boundary faces of group '4'

call getfbr('4', nlelt, lstelt)
 
do ilelt = 1, nlelt
 
  ifac = lstelt(ilelt)
 
  ! Symmetries
 
  itypfb(ifac) = isymet
 
enddo