entropy_viscosity.f90

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module entropy_viscosity
  use num_types, only : rp
  use regularization, only : regularization_t
  use json_module, only : json_file
  use json_utils, only : json_get_or_default
  use field, only : field_t
  use field_math, only : field_cfill, field_glsum, field_cadd, field_copy
  use field_series, only : field_series_t
  use coefs, only : coef_t
  use dofmap, only : dofmap_t
  use time_state, only : time_state_t
  use bdf_time_scheme, only : bdf_time_scheme_t
  use operators, only : div
  use math, only : glmax, absval
  use scratch_registry, only : neko_scratch_registry
  use mesh, only : mesh_t
  use space, only : space_t
  use gather_scatter, only : gs_t
  use gs_ops, only : gs_op_add
  use neko_config, only : neko_bcknd_device
  use device, only : device_memcpy, host_to_device, device_to_host
  use device_math, only : device_col3, device_absval, device_glsum
  use entropy_viscosity_cpu, only : entropy_viscosity_compute_residual_cpu, &
       entropy_viscosity_compute_viscosity_cpu, &
       entropy_viscosity_apply_element_max_cpu, &
       entropy_viscosity_clamp_to_low_order_cpu, &
       entropy_viscosity_smooth_divide_cpu
  use entropy_viscosity_device, only : entropy_viscosity_compute_residual_device, &
       entropy_viscosity_compute_viscosity_device, &
       entropy_viscosity_apply_element_max_device, &
       entropy_viscosity_clamp_to_low_order_device, &
       entropy_viscosity_smooth_divide_device
  implicit none
  private
 
  type, public, extends(regularization_t) :: entropy_viscosity_t
     real(kind=rp) :: c_avisc_entropy
     real(kind=rp) :: c_avisc_low
     type(field_t) :: entropy_residual
     type(field_series_t) :: s_lag
     type(field_t), pointer :: s => null()
     type(field_t), pointer :: u => null()
     type(field_t), pointer :: v => null()
     type(field_t), pointer :: w => null()
     type(field_t), pointer :: h => null()
     type(field_t), pointer :: max_wave_speed => null()
     type(mesh_t), pointer :: msh => null()
     type(space_t), pointer :: xh => null()
     type(gs_t), pointer :: gs => null()
   contains
     procedure, pass(this) :: init => entropy_viscosity_init
     procedure, pass(this) :: free => entropy_viscosity_free
     procedure, pass(this) :: compute => entropy_viscosity_compute
     procedure, pass(this) :: update_lag => entropy_viscosity_update_lag
     procedure, pass(this), private :: compute_residual => entropy_viscosity_compute_residual
     procedure, pass(this), private :: compute_viscosity => entropy_viscosity_compute_viscosity
     procedure, pass(this), private :: smooth_viscosity => entropy_viscosity_smooth_viscosity
     procedure, pass(this), private :: apply_element_max => entropy_viscosity_apply_element_max
     procedure, pass(this), private :: low_order_viscosity => entropy_viscosity_low_order
  end type entropy_viscosity_t
 
  public :: entropy_viscosity_set_fields
 
contains
 
  subroutine entropy_viscosity_init(this, json, coef, dof, reg_coeff)
    class(entropy_viscosity_t), intent(inout) :: this
    type(json_file), intent(inout) :: json
    type(coef_t), intent(in), target :: coef
    type(dofmap_t), intent(in), target :: dof
    type(field_t), intent(in), target :: reg_coeff
 
    call this%init_base(json, coef, dof, reg_coeff)
 
    call json_get_or_default(json, 'c_avisc_low', this%c_avisc_low, 1.0_rp)
    call json_get_or_default(json, 'c_avisc_entropy', this%c_avisc_entropy, 1.0_rp)
 
    call this%entropy_residual%init(dof, 'entropy_residual')
 
    nullify(this%S)
    nullify(this%u)
    nullify(this%v)
    nullify(this%w)
    nullify(this%h)
    nullify(this%max_wave_speed)
    nullify(this%msh)
    nullify(this%Xh)
    nullify(this%gs)
 
  end subroutine entropy_viscosity_init
 
  subroutine entropy_viscosity_free(this)
    class(entropy_viscosity_t), intent(inout) :: this
 
    call this%free_base()
    call this%entropy_residual%free()
    call this%S_lag%free()
 
    nullify(this%S)
    nullify(this%u)
    nullify(this%v)
    nullify(this%w)
    nullify(this%h)
    nullify(this%max_wave_speed)
    nullify(this%msh)
    nullify(this%Xh)
    nullify(this%gs)
 
  end subroutine entropy_viscosity_free
 
  subroutine entropy_viscosity_compute(this, time, tstep, dt)
    class(entropy_viscosity_t), intent(inout) :: this
    type(time_state_t), intent(in) :: time
    integer, intent(in) :: tstep
    real(kind=rp), intent(in) :: dt
    integer :: i, n
 
    n = this%dof%size()
 
    call this%compute_residual(tstep, dt, time%dtlag)
    call this%compute_viscosity(tstep)
 
  end subroutine entropy_viscosity_compute
 
  subroutine entropy_viscosity_compute_residual(this, tstep, dt, dt_lag)
    class(entropy_viscosity_t), intent(inout) :: this
    integer, intent(in) :: tstep
    real(kind=rp), intent(in) :: dt
    real(kind=rp), intent(in) :: dt_lag(10)
    integer :: i, n
    type(field_t), pointer :: us_field, vs_field, ws_field, div_field
    integer :: temp_indices(4)
    real(kind=rp) :: bdf_coeffs(4)
    type(bdf_time_scheme_t) :: bdf_scheme
    real(kind=rp) :: dt_local(10)
 
    if (tstep .le. 3) then
       return
    end if
 
    n = this%dof%size()
    call field_cfill(this%entropy_residual, 0.0_rp, n)
 
    bdf_coeffs = 0.0_rp
    dt_local = dt_lag
 
    call bdf_scheme%compute_coeffs(bdf_coeffs, dt_local, 3)
 
    if (neko_bcknd_device .eq. 1) then
       call entropy_viscosity_compute_residual_device( &
            this%entropy_residual%x_d, &
            this%S%x_d, this%S_lag%lf(1)%x_d, &
            this%S_lag%lf(2)%x_d, this%S_lag%lf(3)%x_d, &
            bdf_coeffs, dt, n)
    else
       call entropy_viscosity_compute_residual_cpu( &
            this%entropy_residual%x, &
            this%S%x, this%S_lag%lf(1)%x, &
            this%S_lag%lf(2)%x, this%S_lag%lf(3)%x, &
            bdf_coeffs, dt, n)
    end if
 
    call neko_scratch_registry%request_field(us_field, temp_indices(1), .false.)
    call neko_scratch_registry%request_field(vs_field, temp_indices(2), .false.)
    call neko_scratch_registry%request_field(ws_field, temp_indices(3), .false.)
    call neko_scratch_registry%request_field(div_field, temp_indices(4), .false.)
 
    if (neko_bcknd_device .eq. 1) then
       call device_col3(us_field%x_d, this%u%x_d, this%S%x_d, n)
       call device_col3(vs_field%x_d, this%v%x_d, this%S%x_d, n)
       call device_col3(ws_field%x_d, this%w%x_d, this%S%x_d, n)
    else
       do i = 1, n
          us_field%x(i,1,1,1) = this%u%x(i,1,1,1) * this%S%x(i,1,1,1)
          vs_field%x(i,1,1,1) = this%v%x(i,1,1,1) * this%S%x(i,1,1,1)
          ws_field%x(i,1,1,1) = this%w%x(i,1,1,1) * this%S%x(i,1,1,1)
       end do
    end if
 
    call div(div_field%x, us_field%x, vs_field%x, ws_field%x, this%coef)
 
    if (neko_bcknd_device .eq. 1) then
       call device_memcpy(this%entropy_residual%x, this%entropy_residual%x_d, &
            n, device_to_host, sync = .false.)
       call device_memcpy(div_field%x, div_field%x_d, n, device_to_host, &
            sync = .true.)
    end if
 
    do i = 1, n
       this%entropy_residual%x(i,1,1,1) = abs(this%entropy_residual%x(i,1,1,1) &
            + div_field%x(i,1,1,1))
    end do
 
    if (neko_bcknd_device .eq. 1) then
       call device_memcpy(this%entropy_residual%x, this%entropy_residual%x_d, &
            n, host_to_device, sync = .false.)
    end if
 
    call neko_scratch_registry%relinquish_field(temp_indices)
 
  end subroutine entropy_viscosity_compute_residual
 
  subroutine entropy_viscosity_compute_viscosity(this, tstep)
    class(entropy_viscosity_t), intent(inout) :: this
    integer, intent(in) :: tstep
    integer :: i, n, temp_indices(1)
    real(kind=rp) :: s_mean, n_s
    type(field_t), pointer :: temp_field
 
    n = this%dof%size()
 
    if (tstep .le. 3) then
       call field_cfill(this%reg_coeff, 0.0_rp, n)
       return
    end if
 
    call neko_scratch_registry%request_field(temp_field, temp_indices(1), .false.)
 
    call field_cfill(temp_field, 1.0_rp, n)
    s_mean = field_glsum(this%S, n) / field_glsum(temp_field, n)
 
    call field_copy(temp_field, this%S, n)
    call field_cadd(temp_field, -s_mean, n)
 
    if (neko_bcknd_device .eq. 1) then
       call device_absval(temp_field%x_d, n)
       call device_memcpy(temp_field%x, temp_field%x_d, n, device_to_host, &
            sync = .true.)
    else
       call absval(temp_field%x, n)
    end if
 
    ! Normalization factor n_S = |S-S_mean|_inf
    n_s = glmax(temp_field%x, n)
 
    call neko_scratch_registry%relinquish_field(temp_indices)
 
    if (n_s < 1.0e-12_rp) then
       n_s = 1.0e-12_rp
    end if
 
    ! entropy viscosity = c_avisc_entropy * h^2 * entropy_residual / n_S
    if (neko_bcknd_device .eq. 1) then
       call entropy_viscosity_compute_viscosity_device( &
            this%reg_coeff%x_d, this%entropy_residual%x_d, &
            this%h%x_d, this%c_avisc_entropy, n_s, n)
    else
       call entropy_viscosity_compute_viscosity_cpu( &
            this%reg_coeff%x, this%entropy_residual%x, &
            this%h%x, this%c_avisc_entropy, n_s, n)
    end if
 
    ! effective viscosity = min(entropy viscosity, low-order viscosity)
    if (neko_bcknd_device .eq. 1) then
       call entropy_viscosity_clamp_to_low_order_device( &
            this%reg_coeff%x_d, this%h%x_d, this%max_wave_speed%x_d, &
            this%c_avisc_low, n)
    else
       call entropy_viscosity_clamp_to_low_order_cpu( &
            this%reg_coeff%x, this%h%x, this%max_wave_speed%x, &
            this%c_avisc_low, n)
    end if
 
    call this%apply_element_max()
 
    call this%smooth_viscosity()
 
  end subroutine entropy_viscosity_compute_viscosity
 
  subroutine entropy_viscosity_smooth_viscosity(this)
    class(entropy_viscosity_t), intent(inout) :: this
    integer :: n
    type(field_t), pointer :: temp_field, mult_field
    integer :: temp_indices(2)
 
    n = this%dof%size()
 
    call neko_scratch_registry%request_field(temp_field, temp_indices(1), .false.)
    call neko_scratch_registry%request_field(mult_field, temp_indices(2), .false.)
 
    call field_copy(temp_field, this%reg_coeff, n)
    call this%gs%op(temp_field, gs_op_add)
 
    call field_cfill(mult_field, 1.0_rp, n)
    call this%gs%op(mult_field, gs_op_add)
 
    if (neko_bcknd_device .eq. 1) then
       call entropy_viscosity_smooth_divide_device( &
            this%reg_coeff%x_d, temp_field%x_d, mult_field%x_d, n)
    else
       call entropy_viscosity_smooth_divide_cpu( &
            this%reg_coeff%x, temp_field%x, mult_field%x, n)
    end if
 
    call neko_scratch_registry%relinquish_field(temp_indices)
 
  end subroutine entropy_viscosity_smooth_viscosity
 
  subroutine entropy_viscosity_apply_element_max(this)
    class(entropy_viscosity_t), intent(inout) :: this
    integer :: lx
 
    lx = this%Xh%lx
 
    if (neko_bcknd_device .eq. 1) then
       call entropy_viscosity_apply_element_max_device( &
            this%reg_coeff%x_d, lx, this%msh%nelv)
    else
       call entropy_viscosity_apply_element_max_cpu( &
            this%reg_coeff%x, lx, this%msh%nelv)
    end if
 
  end subroutine entropy_viscosity_apply_element_max
 
  subroutine entropy_viscosity_set_fields(this, S, u, v, w, h, max_wave_speed, &
       msh, Xh, gs)
    class(entropy_viscosity_t), intent(inout) :: this
    type(field_t), target, intent(inout) :: s
    type(field_t), target, intent(in) :: u, v, w, h, max_wave_speed
    type(mesh_t), target, intent(in) :: msh
    type(space_t), target, intent(in) :: xh
    type(gs_t), target, intent(in) :: gs
 
    this%S => s
    this%u => u
    this%v => v
    this%w => w
    this%h => h
    this%max_wave_speed => max_wave_speed
    this%msh => msh
    this%Xh => xh
    this%gs => gs
 
    call this%S_lag%init(s, 3)
 
  end subroutine entropy_viscosity_set_fields
 
  subroutine entropy_viscosity_update_lag(this)
    class(entropy_viscosity_t), intent(inout) :: this
 
    call this%S_lag%update()
 
  end subroutine entropy_viscosity_update_lag
 
  pure function entropy_viscosity_low_order(this, i) result(visc)
    class(entropy_viscosity_t), intent(in) :: this
    integer, intent(in) :: i
    real(kind=rp) :: visc
 
    visc = this%c_avisc_low * this%h%x(i,1,1,1) * this%max_wave_speed%x(i,1,1,1)
 
  end function entropy_viscosity_low_order
 
end module entropy_viscosity