VMFL040

VMFL040
Separated Turbulent Flow in a Diffuser

Overview

Reference D.M. Driver. "Reynolds shear stress measurements in a separated boundary layer flow". AIAA-91-1787. 1991.

Solver Ansys CFX, Ansys Fluent

Physics/Models SST model, Adverse pressure gradient, flow separation

Input Files

diffuser-sep.def for Ansys CFX

VMFL040A_diffuser-sep.cas for Ansys Fluent

Project Files Link to Project Files Download Page

Test Case

The test case geometry is shown in Figure 102: Sketch of Flow Domain. It consists of an axisymmetric diffuser with an internally mounted cylinder along the centre line. The curvature of the diffuser wall results in an adverse pressure gradient. A relatively short separation region was detected in the experiment.

Figure 102: Sketch of Flow Domain

This figure is not to scale.

Material Properties	Geometry	Boundary Conditions
Density: 1 kg/m³ Viscosity: 1.5 X 10^-5 kg/m-s	Diameter of the cylinder = 140 mm Length of the domain = 1100 mm	Velocity profile at inlet with average velocity = 29 m/s Outer wall modeled as a slip (inviscid) wall

Material Properties

Geometry

Boundary Conditions

Density: 1 kg/m³

Viscosity: 1.5 X 10^-5 kg/m-s

Diameter of the cylinder = 140 mm

Length of the domain = 1100 mm

Velocity profile at inlet with average velocity = 29 m/s

Outer wall modeled as a slip (inviscid) wall

Analysis Assumptions and Modeling Notes

The flow is steady. SST model is used for turbulence.

Results Comparison for Ansys Fluent

Figure 103: Comparison of Skin Friction Coefficient on the Cylinder Wall

Results Comparison for Ansys CFX

Figure 104: Comparison of Skin Friction Coefficient on the Cylinder Wall