setup_gradients Subroutine

    subroutine setup_gradients(control, scheme, flow, dims)
      !< Memoery allocation to the gradient variables and 
      !< setup pointer to the slice to the main gradient variable
      !< based on the various models being used.

      implicit none
      type(controltype), intent(in) :: control
      !< Control parameters
      type(schemetype) , intent(in) :: scheme
      !< finite-volume Schemes
      type(flowtype)   , intent(in) :: flow
      !< Information about fluid flow: freestream-speed, ref-viscosity,etc.
      type(extent), intent(in) :: dims
      !< Extent of the domain:imx,jmx,kmx

      DebugCall("setup_gradients")

        imx = dims%imx
        jmx = dims%jmx
        kmx = dims%kmx

        n_var = control%n_var
        R_gas = flow%R_gas

      if(flow%mu_ref/=0)then

        call get_n_grad(scheme)
        !call allocate_memory()
        call alloc(gradqp_x, 0, imx, 0, jmx, 0, kmx, 1, n_grad, AErrMsg("gradqp_x"))
        call alloc(gradqp_y, 0, imx, 0, jmx, 0, kmx, 1, n_grad, AErrMsg("gradqp_y"))
        call alloc(gradqp_z, 0, imx, 0, jmx, 0, kmx, 1, n_grad, AErrMsg("gradqp_z"))

        ! Linking pointer to laminar gradients
        !call setup_laminar_grad()
        DebugCall('setup_laminar_grad')
        !< Setup Pointer to the main array which stores gradient 
        !< all variables with x, y, z

        gradu_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, 1)
        gradv_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, 2)
        gradw_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, 3)
        gradT_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, 4)

        gradu_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, 1)
        gradv_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, 2)
        gradw_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, 3)
        gradT_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, 4)

        gradu_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, 1)
        gradv_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, 2)
        gradw_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, 3)
        gradT_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, 4)

        ! Linking pointer to turbulent gradients
        select case (trim(scheme%turbulence))
          
          case('none')
            !do nothing
            continue

          case('sa', 'saBC')
            !call setup_sa_grad()
            DebugCall("setup_sa_grad")
            gradtv_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, 5)
            gradtv_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, 5)
            gradtv_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, 5)

          case('sst', 'sst2003')
            !< Setup Pointer to the main array which stores gradient 
            !< all variables with x, y, z
            DebugCall('setup_sst_grad')

            gradtk_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, 5)
            gradtw_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, 6)

            gradtk_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, 5)
            gradtw_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, 6)

            gradtk_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, 5)
            gradtw_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, 6)

          case('kkl')
            !call setup_kkl_grad()
            DebugCall('setup_kkl_grad')

            gradtk_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, 5)
            gradtkl_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, 6)

            gradtk_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, 5)
            gradtkl_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, 6)

            gradtk_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, 5)
            gradtkl_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, 6)

          case DEFAULT
            Fatal_error

        end select

        !Transition modeling
        select case(trim(scheme%transition))

          case('lctm2015')
            !call setup_lctm2015_grad()
            gradtgm_x(0:imx, 0:jmx, 0:kmx) => gradqp_x(:, :, :, n_grad)
            gradtgm_y(0:imx, 0:jmx, 0:kmx) => gradqp_y(:, :, :, n_grad)
            gradtgm_z(0:imx, 0:jmx, 0:kmx) => gradqp_z(:, :, :, n_grad)

          case('none','bc')
            !do nothing
            continue

          case DEFAULT
            Fatal_error

        end Select

      end if
    end subroutine setup_gradients