Understanding Boundary Conditions in STAR-CCM

Types of Boundary conditions in STAR-CCM+

1) Velocity Inlet - It controls how you define the velocity at the inlet of the flow domain

2) Mass Flow Inlet - The mass flow rate at the inlet is specified, from which the velocity can be calculated.

3) Stagnation Inlet - For this boundary type, you always set the total pressure upstream of the simulation domain.

4) Free stream - In this boundary type, specifying the Mach number, static pressure and static temperature values is a default option.

5) Wall - This boundary type defines how a wall surface acts on a fluid passing through it. A wall boundary can be set as Slip or No Slip.

6) Pressure Outlet - The pressure at the outlet is specified

7) Outlet - Either split ratios or mass fluxes is specified at the outlet

Note: The value of pressure at an outlet exposed to atmosphere is zero, because the pressure is specified as gauge pressure (Relative to atmospheric pressure).

A pipe is modelled, meshed and the Boundary conditions are set as shown below:

The pipe is modelled by first drawing the circle (profile) of radius 10 mm then the path is created on a plane perpendicular to it each line of length 50 mm. The sweep option is used to create the model.

The meshed geometry as shown below:

The mesh controls are:

Section plane to show the detailed view of mesh:

Before setting up the boundary conditions the physics models to be solved should be selected as follows:

The Boundary conditions are set as follows:

The Simulation file: