udfGetElmData()

Syntax

data = udfGetElmData( udfHd, dataName ) ;

Type

User Defined Element

Parameters

udfHd

The opaque handle (pointer) which was passed to the user function.

dataName (integer)

Symbolic name of the requested data.

UDF_ELM_VELOCITY

Velocity.

UDF_ELM_ACCELERATION

Acceleration.

UDF_ELM_PRESSURE

Pressure.

UDF_ELM_TEMPERATURE

Temperature.

UDF_ELM_DENSITY

Density.

UDF_ELM_SPECIES

Species.

UDF_ELM_VISCOSITY

Viscosity.

UDF_ELM_EDDY_VISCOSITY

Turbulence eddy viscosity.

UDF_ELM_KINETIC_ENERGY

Turbulence kinetic energy.

UDF_ELM_EDDY_FREQUENCY

Turbulence eddy frequency.

UDF_ELM_GRAD_VELOCITY

Gradient of velocity.

UDF_ELM_GRAD_PRESSURE

Gradient of pressure.

UDF_ELM_GRAD_TEMPERATURE

Gradient of temperature.

UDF_ELM_GRAD_SPECIES

Gradient of species.

UDF_ELM_MESH_DISPLACEMENT

Mesh displacement.

UDF_ELM_MESH_VELOCITY

Mesh velocity.

UDF_ELM_MESH_GRAD_DISPLACEMENT

Gradient of mesh displacement.

UDF_ELM_MESH_GRAD_VELOCITY

Gradient of mesh velocity.

UDF_ELM_TURBULENCE_Y

Distance to nearest turbulence wall.

UDF_ELM_TURBULENCE_YPLUS

Turbulence y+ based on distance to nearest turbulence wall and shear at that wall.

UDF_ELM_VISCOELASTIC

Viscoelastic.

Return Value

data (Real*)

Pointer to one, two, or three dimensional real array of the requested data. The dimensions of the array depend on dataName as follows. If the third (slowest) dimension of the array is equal to one, then the array may be treated as two dimensional. If the second dimension is likewise one, then the array is one dimensional. The x, y, z components of the gradient for gradient quantities are always contained in the last nontrivial dimension.

Table 1.

dataName	First Dimension	Second Dimension	Third Dimension
UDF_ELM_VELOCITY	nItems	3	1
UDF_ELM_ACCLERATION	nItems	3	1
UDF_ELM_PRESSURE	nItems	1	1
UDF_ELM_TEMPERATURE	nItems	1	1
UDF_ELM_DENSITY	nItems	1	1
UDF_ELM_SPECIES	nItems	udfGetNumSpecs()	1
UDF_ELM_VISCOSITY	nItems	1	1
UDF_ELM_EDDY_VISCOSITY	nItems	1	1
UDF_ELM_KINETIC_ENERGY	nItems	1	1
UDF_ELM_EDDY_FREQUENCY	nItems	1	1
UDF_ELM_GRAD_VELOCITY	nItems	3	3
UDF_ELM_GRAD_PRESSURE	nItems	3	1
UDF_ELM_GRAD_TEMPERATURE	nItems	3	1
UDF_ELM_GRAD_SPECIES	nItems	udfGetNumSpecs()	3
UDF_ELM_MESH_DISPLACEMENT	nItems	3	1
UDF_ELM_MESH_VELOCITY	nItems	3	1
UDF_ELM_MESH_GRAD_DISPLACEMENT	nItems	3	3
UDF_ELM_MESH_GRAD_VELOCITY	nItems	3	3
UDF_ELM_TURBULENCE_Y	nItems	1	1
UDF_ELM_TURBULENCE_YPLUS	nItems	1	1
UDF_ELM_VISCOELASTIC	nItems	6	1

Description

Real* data ;
Real* grad_x ;
Real* grad_y ;
Real* grad_z ;
Real* s_x ;
Real* s_y ;
Real* s_z ;
Real u, v, w ;
Real u_x, v_x, w_x, u_y, v_y, w_y, u_z, v_z, w_z ;
Real spec_x, spec_y, spec_z ;
Integer elem, nSpecs, specId ;
...
data = udfGetElmData( udfHd, UDF_ELM_VELOCITY ) ;
for ( elem = 0 ; elem < nItems ; elem++ ) {
  u = data[0*nItems+elem] ;
  v = data[1*nItems+elem] ;
  w = data[2*nItems+elem] ;
  ...
}
...
data = udfGetElmData( udfHd, UDF_ELM_GRAD_VELOCITY ) ;
for ( elem = 0 ; elem < nItems ; elem++ ) {
   u_x = data[0*nItems+elem] ;
   v_x = data[1*nItems+elem] ;
   w_x = data[2*nItems+elem] ;
   u_y = data[3*nItems+elem] ;
   v_y = data[4*nItems+elem] ;
   w_y = data[5*nItems+elem] ;
   u_z = data[6*nItems+elem] ;
   v_z = data[7*nItems+elem] ;
   w_z = data[8*nItems+elem] ;
   ...
}
...
data = udfGetElmData( udfHd, UDF_ELM_GRAD_SPECIES ) ;
nSpecs = udfGetNumSpecs( udfHd ) ;
for ( specId = 0 ; specId < nSpecs ; specId++ ) {
   for ( elem = 0 ; elem < nItems ; elem++ ) {
     /* 3 components of gradient of species */
     spec_x = data[nItems*(0*nSpecs+specId)+elem] ;
     spec_y = data[nItems*(1*nSpecs+specId)+elem] ;
     spec_z = data[nItems*(2*nSpecs+specId)+elem] ;
     ...
   }
}
/* Alternative coding of the above. */
/* grad_? are pointers to 2-D arrays, and */
/* s_? are pointers to 1-D arrays. */
data = udfGetElmData( udfHd, UDF_ELM_GRAD_SPECIES ) ;
nSpecs = udfGetNumSpecs( udfHd ) ;
grad_x = &data[0*nItems*nSpecs] ;
grad_y = &data[1*nItems*nSpecs] ;
grad_z = &data[2*nItems*nSpecs] ;
for ( specId = 0 ; specId < nSpecs ; specId++ ) {
   s_x = &grad_x[nItems*specId] ;
   s_y = &grad_y[nItems*specId] ;
   s_z = &grad_z[nItems*specId] ;
   for ( elem = 0 ; elem < nItems ; elem++ ) {
      /* 3 components of gradient of species */
      spec_x = s_x[elem] ;
      spec_y = s_y[elem] ;
      spec_z = s_z[elem] ;
      ...
   }
}

The quantities UDF_ELM_TURBULENCE_Y and UDF_ELM_TURBULENCE_YPLUS are based on the distance to the nearest turbulence wall. These are defined by TURBULENCE_WALL and SIMPLE_BOUNDARY_CONDITION type=wall commands. UDF_ELM_TURBULENCE_YPLUS also uses the shear at these walls. The data for these two quantities are current (computed at the end of each stagger) while the other quantities are computed only at the end of each time step.

Errors

• This routine expects a valid udfHd.
• This routine may only be called within a Body Force, Material Model or Component Model user function.
• dataName must be one of the values given above.
• The problem must contain the equation associated with the requested data.