FFTGradient

Tensor gradient.

Compute the gradient component of a real space tensor along a selected axis using the spectral gradient. Internally this involves a forward and a backward Fourier transform and inbetween a multiplication with the $var element = document.getElementById("moose-equation-80383388-7c8b-4eaf-b494-3bb172909c5b");katex.render("\\vec k", element, {displayMode:false,throwOnError:false});$ vector and the imaginary unit $var element = document.getElementById("moose-equation-8634f589-1fdc-46c2-af96-49b2cb87d938");katex.render("i", element, {displayMode:false,throwOnError:false});$ .

Example Input File Syntax

[TensorComputes]
  [Solve]
    [to_k]
      type = ForwardFFT
      buffer = cbar
      input = c
    []
    [dc_dx]
      type = FFTGradient
      buffer = dc_dx
      input = c
      direction = 0                    # 0:x, 1:y, 2:z
    []
  []
[]
!listing-end

Input Parameters

bufferThe buffer this compute is writing to
C++ Type:std::string
Controllable:No
Description:The buffer this compute is writing to
directionWhich axis to take the gradient along.
C++ Type:MooseEnum
Options:X, Y, Z
Controllable:No
Description:Which axis to take the gradient along.
inputInput buffer name
C++ Type:std::string
Controllable:No
Description:Input buffer name

Required Parameters

input_is_reciprocalFalseInput buffer is already in reciprocal space
Default:False
C++ Type:bool
Controllable:No
Description:Input buffer is already in reciprocal space

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Controllable:No
Description:Set the enabled status of the MooseObject.

Advanced Parameters

Input Files

(test/tests/gradient/gradient.i)

(test/tests/gradient/gradient.i)

[Domain]
  dim = 3
  nx = 40
  ny = 40
  nz = 40
  xmax = ${fparse pi*2}
  ymax = ${fparse pi*4}
  zmax = ${fparse pi*6}
  mesh_mode = DUMMY
[]

[TensorBuffers]
  [s]
  []
  [gradx_s]
  []
  [grady_s]
  []
  [gradz_s]
  []
  [cx]
  []
  [cy]
  []
  [cz]
  []
  [diff]
  []
[]

[TensorComputes]
  [Initialize]
    [sin]
      type = ParsedCompute
      buffer = s
      extra_symbols = true
      expression = 'sin(x)+sin(y)+sin(z)'
    []
    [cosx]
      type = ParsedCompute
      buffer = cx
      extra_symbols = true
      expression = 'cos(x)'
    []
    [cosy]
      type = ParsedCompute
      buffer = cy
      extra_symbols = true
      expression = 'cos(y)'
    []
    [cosz]
      type = ParsedCompute
      buffer = cz
      extra_symbols = true
      expression = 'cos(z)'
    []
    [gradx_sin]
      type = FFTGradient
      buffer = gradx_s
      input = s
      direction = x
    []
    [grady_sin]
      type = FFTGradient
      buffer = grady_s
      input = s
      direction = y
    []
    [gradz_sin]
      type = FFTGradient
      buffer = gradz_s
      input = s
      direction = z
    []
    [diff]
      type = ParsedCompute
      buffer = diff
      inputs = 'gradx_s grady_s gradz_s cx cy  cz'
      expression = 'abs(gradx_s - cx)+abs(grady_s - cy)+abs(gradz_s - cz)'
    []
  []
[]

[Postprocessors]
  [diff]
    type = TensorIntegralPostprocessor
    buffer = diff
  []
[]

[Problem]
  type = TensorProblem
[]

[Executioner]
  type = Transient
  num_steps = 1
[]

[Outputs]
  csv = true
[]

Example Input File Syntax
Input Parameters
Input Files