Tutorial:Modeling Flow-Induced(Aeroacoustic)Noi Problems Using FLUENT
Introduction
This tutorial demonstrates how to model2D turbulentflow across a circular cylinder using large eddy simulation(LES)and computeflow-induced(aeroacoustic)noi using FLUENT’s acoustics model.
You will learn how to:
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•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 tup and solution procedures.Some steps will not be shown explicitly.
In this tutorial you will u the acoustics model.If you have not ud this feature before,first read Chapter21,Predicting Aerodynamically Generated Noi,of the FLUENT6.2 Ur’s Guide臭肥皂
Modeling Flow-Induced(Aeroacoustic)Noi Problems Using FLUENT
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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 bad 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怎样预防校园欺凌
Figure1:Computational Domain
Preparation
我想有个星期八1.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 t up the acoustics model,you can reduce the computing time requirements considerably by starting at Step7and using the provided ca and datafiles.
Modeling Flow-Induced(Aeroacoustic)Noi Problems Using FLUENT Step1:Grid
1.Read the gridfile cylinder2d.msh.
File−→Read−→Ca...
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.
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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 Rever Cuthill-McKee method:疑心重
zones,cells,faces,done.
Bandwidth reduction=32634/253=128.99
Done.
Modeling Flow-Induced(Aeroacoustic)Noi Problems Using FLUENT
4.Display the grid.
Display−→
(a)Display the grid with the default ttings(Figure2).
U the middle mou button to zoom in on the image so you can e the mesh
near the cylinder(Figure3).
Figure2:Grid Display
原始之爱Modeling Flow-Induced(Aeroacoustic)Noi Problems Using FLUENT
Figure3:The Grid Around the Cylinder
Quadrilateral cells are ud for this LES simulation becau they generate less numerical diffusion than triangular cells.The cell size should be small enough to capture the relevant turbulence length scales,and to make the numerical diffusion smaller than the subgrid-scale turbulence viscosity.The mesh for this tutorial has been kept coar in order to speed up the calculations.A high quality LES simulation will require afiner mesh near the cylinder wall.
