# Surface Data

This result control item allows performing field calculation based on geometry faces. The following types are available:

• Area average: this function provides averaging of field variable over the face areas. The user can choose a number of faces to perform the operation on.
• Area integral: this function calculates integral of field variables over a face. The user can choose a number of faces to perform the operation on.
• Dimensionless wall distance Y-plus: this function will trigger the calculation of the dimensionless wall distance y+
${y}^{+}$

. After the job is finished, the wall distance will be calculated from the solution fields. The wall distance can be viewed in the post processor.

Important

If ‘Wall funtions’ are used in the boundary conditions, y+

${y}^{+}$

values between 30 and 200 are recommended. Greater values lead to greater discretization errors for boundary layers and wall shear stresses.

Important

If ‘zero Gradient’ settings are used in the boundary conditions, y+

${y}^{+}$

values between 0 and 1.5 are recommended.

Important

In No case are y+

${y}^{+}$

values between 3 and 30 desirable.