## *MASS FLOW

Keyword type: step

This option allows the specification of a mass flow through a face in 3-D Navier-Stokes calculations.

In order to specify which face the flow is entering or leaving the faces are numbered. The numbering depends on the element type.

For hexahedral elements the faces are numbered as follows (numbers are node numbers):

• Face 1: 1-2-3-4
• Face 2: 5-8-7-6
• Face 3: 1-5-6-2
• Face 4: 2-6-7-3
• Face 5: 3-7-8-4
• Face 6: 4-8-5-1

for tetrahedral elements:

• Face 1: 1-2-3
• Face 2: 1-4-2
• Face 3: 2-4-3
• Face 4: 3-4-1

for wedge elements:

• Face 1: 1-2-3
• Face 2: 4-5-6
• Face 3: 1-2-5-4
• Face 4: 2-3-6-5
• Face 5: 3-1-4-6

The mass flow is entered as a uniform flow with flow type label Mx where x is the number of the face. Right now, only zero mass flow is allowed, i.e. no flow is entering or leaving the domain. There are no parameters for this keyword card.

In order to apply a mass flow to a surface the element set label underneath may be replaced by a surface name. In that case the mass flow type label takes the value “M” without any number following.

First line:

• *MASS FLOW

Following line:

• Element number or element set label.
• Mass flow type label.
• Zero.
Repeat this line if needed.

Example:

*MASS FLOW
20,M2


assigns a zero mass flow to face 2 of element 20.

Example files: bumpsubfine (large fluid examples).