Tutorial:Modeling Flow-Induced(Aeroacoustic)Noise Problems Using FLUENT
Introduction
This tutorial demonstrates how to model2D turbulentflow across a circular cylinder using large eddy simulation(LES)and computeflow-induced(aeroacoustic)noise using FLUENT’s acoustics model.
You will learn how to:
•Perform a2D large eddy simulation.
•Set parameters for an aeroacoustic calculation.
•Save acoustic source data for an acoustic calculation.
•Calculate acoustic pressure signals.
•Postprocess aeroacoustic results.
Prerequisites
This tutorial assumes that you are familiar with the FLUENT interface and that you have a good understanding of basic setup and solution procedures.Some steps will not be shown explicitly.
In this tutorial you will use the acoustics model.If you have not used this feature before,first read Chapter21,Predicting Aerodynamically Generated Noise,of the FLUENT6.2 User’s Guide
Modeling Flow-Induced(Aeroacoustic)Noise Problems Using FLUENT
Problem Description
The problem considers turbulent airflow over a2D circular cylinder at a free stream ve-locity(U)of69.2m/s.The cylinder diameter(D)is1.9cm.The Reynolds number based on the diameter is90,000.The computational domain(Figure1)extends5D upstream and 20D downstream of the cylinder.
U = 69.2 m/s D = 1.9 cm
Figure1:Computational Domain
Preparation
1.Copy thefile cylinder2d.msh to your working directory.
2.Start the2D version of FLUENT.
Approximately2.5hours of CPU time is required to complete this tutorial.If you are interested exclusively in learning how to set up the acoustics model,you can reduce the computing time requirements considerably by starting at Step7and using the provided case and datafiles.
Modeling Flow-Induced(Aeroacoustic)Noise Problems Using FLUENT Step1:Grid
1.Read the gridfile cylinder2d.msh.
File−→Read−→Case...
As FLUENT reads the gridfile,it will report its progress in the console window.
Since the grid for this tutorial was created in meters,there is no need to rescale the grid.Check that the domain extends in the x-direction from-0.095m to0.38m.
2.Check the grid.
Grid−→Check
FLUENT will perform various checks on the mesh and will report the progress in the console window.Pay particular attention to the reported minimum volume.Make sure this is a positive number.
3.Reorder the grid.
Grid−→Reorder−→Domain
To speed up the solution procedure,the mesh should be reordered,which will substan-tially reduce the bandwidth and make the code run faster.
FLUENT will report its progress in the console window:
>>Reordering domain using Reverse Cuthill-McKee method:
zones,cells,faces,done.
Bandwidth reduction=32634/253=128.99
Done.
