# Separated Laminar Flow Over a Blunt Plate

In this application, AcuSolve is used to simulate the separation of laminar flow over a blunt plate. AcuSolve results are compared with experimental results as described in J.C. Lane and R.I. Loehrke (1980). The close agreement of AcuSolve results with the experimental results validates the ability of AcuSolve to model cases with external laminar flow including separation.

## Problem Description

^{3}and a dynamic viscosity of 1.7894 X 10

^{-5}kg/m-s. The resulting Reynolds number for the flow, based on the plate thickness, is approximately 227. This indicates that the flow over the plate is laminar. As the fluid flows past the leading edge of the plate, the pressure decreases, resulting in a separation region downstream of the leading edge. At some distance downstream from the leading edge, the pressure gradient decreases, and viscous forces cause the recirculation zone to dissipate, allowing the flow to reattach to the plate.

## AcuSolve Results

Downstream of the leading edge, the flow eventually reattaches to the plate at the point where the shear stress parallel to the wall passes from negative through zero to positive. The reattachment point is 0.37 m from the leading edge of the plate and corresponds to the trailing edge of the contours.

AcuSolve xreattach | AcuSolve xreattach/T | Experimental xreattach/T | Percent error (%) |
---|---|---|---|

0.37 | 4.11 | 4.0 | 2.8 |

## Summary

In this application, a constant flow inlet velocity and symmetric boundary conditions were used to model 2D flow over a blunt plate. The AcuSolve solution compares well with experimental results for the separation of laminar flow over a blunt plate. The non-dimensional reattachment length obtained from the AcuSolve steady state solution compares well with the experimental solution, with an error of less than 3.0 percent. The results of this simulation validate the ability of AcuSolve to accurately predict the reattachment point in cases with external, laminar flow with separation.

## Simulation Settings for Separated Laminar Flow over a Blunt Plate

HyperMesh CFD database file: <your working directory>\blunt_plate_laminar\blunt_plate_laminar.hm

Global

- Problem Description
- Analysis type - Steady State
- Turbulence equation - Laminar

- Auto Solution Strategy
- Relaxation Factor -
`0.2`

- Relaxation Factor -
- Material Model
- Fluid
- Density -
`1.0`kg/m3 - Viscosity -
`1.7894e-005`kg/m-sec

- Density -

Model

- Fluid
- Volumes
- Fluid
- Element Set
- Material model - Fluid

- Element Set

- Fluid
- Surfaces
- Back
- Simple Boundary Condition
- Type - Symmetry

- Simple Boundary Condition
- Freestream
- Simple Boundary Condition
- Type - Slip

- Simple Boundary Condition
- Front
- Simple Boundary Condition
- Type - Symmetry

- Simple Boundary Condition
- Inlet
- Simple Boundary Condition
- Type - Inflow
- Inflow type - Velocity
- Inflow velocity type - Cartesian
- X Velocity -
`0.045133`m/s

- Simple Boundary Condition
- Outflow
- Simple Boundary Condition
- Type - Outflow

- Simple Boundary Condition
- Plate
- Simple Boundary Condition
- Type - Wall

- Simple Boundary Condition
- Symmetry
- Simple Boundary Condition
- Type - Symmetry

- Simple Boundary Condition

- Back

## References

J.C. Lane and R.I. Loehrke. "Leading Edge Separation from a Blunt Plate at Low Reynolds Number". Journal of Fluids Engineering. 102(4):494-496. 1980.