VMFL019

VMFL019
Transient Flow Near a Wall Set in Motion

Overview

Reference

H. Schlichting, K. Gersten, Boundary Layer Theory, 8th Edition, pp. 126-127, 2000

Solver Ansys Fluent, Ansys CFX

Physics/Models Unsteady flow, moving wall

Input File

VMFL019_FLUENT.cas for Ansys Fluent

VMFL019_CFX.def for Ansys CFX

Project Files Link to Project Files Download Page

Test Case

Flow near a wall suddenly set into motion is modeled. The start up flow is modeled as a transient problem with a constant wall-velocity at t (time) > 0. The flow is highly viscous and the velocity is 0 at t= 0.

Figure 48: Flow Domain

Material Properties	Geometry	Boundary Conditions
Density = 1000 kg/m³ Viscosity = 1 kg/m-s	Dimensions of the domain: 0.75 m X 0.3 m	Velocity of the moving wall = 0.01 m/s Gauge Pressure at Inlet = 0 N/m² Gauge Pressure at Outlet = 0 N/m²

Material Properties

Geometry

Boundary Conditions

Density = 1000 kg/m³

Viscosity = 1 kg/m-s

Dimensions of the domain: 0.75 m X 0.3 m

Velocity of the moving wall = 0.01 m/s

Gauge Pressure at Inlet = 0 N/m²

Gauge Pressure at Outlet = 0 N/m²

Analysis Assumptions and Modeling Notes

The pressure based solver is used in Ansys Fluent. Pressure boundaries are specified to model the driving head in the direction of flow. The fluid is at rest initially (t = 0). The similarity parameter is defined as:

Where ν is the kinematic viscosity.

Results Comparison using Ansys Fluent

Figure 49: Comparison of Velocity Profile Near the Wall at Outlet

Results Comparison using Ansys CFX

Figure 50: Comparison of Velocity Profile Near the Wall at Outlet