**process gradient

Description

Calculate the gradient of \((U1,U2)\) with respect to the given direction.

Syntax

**process gradient dir

where dir should be either X, Y or Z.

The resulting (integ) field are named gradXU1, gradXU2 (resp. with Y or Z).

Example

****post_processing
 ***global_post_processing
  **file node
  **nset ALL_NODE
  **process gradient X
  **process gradient Y

 ***local_post_processing
  **file integ
  **elset ALL_ELEMENT
  **process function
   *output epsilon12
   *expression 0.5*(gradXU2 + gradYU1) ;
****return