Tech Briefs

The Multiple Reference Frame Feature in ADINA CFD

In this example, we solve a CFD problem using the new Multiple Reference Frame feature available in ADINA.

The problem is illustrated in the schematic below. Fluid flows through a 3-dimensional channel with two impellers rotating at different frequencies (Ω21=6). A normal traction is applied at the inlet, and a mass ratio loading is applied at the lower half of the inlet. The mesh used, which remains stationary during the simulation, is shown in the next figure, followed by the pressure plot calculated at the central cross-sectional plane. The above animation shows the mass transfer in the same plane.

In this problem, it is assumed that the flow between the zones of the impellers and the main flow is practically uniform. Hence instead of moving the impellers, these are modeled as stationary and equivalent forces are applied in the respective frames.

Schematic of Problem

The Fluid Mesh

Pressure Plot in the Central Cross-Sectional Plane

Generally, for problems with moving/rotating parts, two approaches in ADINA CFD can be used. If the unsteady interactions are strong, the sliding mesh method should be used for a time-accurate transient analysis. However, if the unsteady interactions are weak, then the Multiple Reference Frame feature can be used as given here.