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#1 |
New Member
Matthew
Join Date: Aug 2017
Posts: 28
Rep Power: 9 ![]() |
Hi, I am building a simple model for a fully turbulent flow passing through a pipe. My idea is to use the “turbulentInlet” type at the inlet to achieve a random turbulence, and then to let the flow go through a long enough pipe, to achieve fully developed turbulence at the end of the pipe.
However, the model I built doesn’t show an expected result. The movement of turbulent flow is just on the plane of inlet, like it’s showing in the picture 1. How to let the turbulence go along the pipe? 1.jpg picture 1 By the way, in the results of mine, at the time step of 0.001, the velocity of flow is -10m/s all over the pipe (picture 2 and 3). Is this reasonable? And why? The length of my pipe is 200m, the velocity of the flow is -10m/s. The deltaT and writeInterval I used in controlDict are 0.001 and 1 respectively. 00.jpg picture 2. the velocity of t=0 11.jpg picture 3. the velocity of t=0.001 The code of U is as follows and the icoFoam is used in this model. Code:
dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { inlet0 { type turbulentInlet; referenceField uniform (0 -10 0); fluctuationScale (0.5 0.5 0.5); value uniform (0 -10 0); } outlet { type pressureInletOutletVelocity; inletValue uniform (0 0 0); value uniform (0 0 0); } sideWall { type zeroGradient; } } ![]() ![]() |
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#2 | |
Senior Member
Robert
Join Date: May 2015
Location: Bremen, GER
Posts: 292
Rep Power: 12 ![]() |
Quote:
So i guess your solver might not be able to support turbulence. Have you tried transient turbulent solvers like pisoFoam? And remember to include a turbulence model (RAS/LES) in your turbulenceProperties.dict. |
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#3 | |
New Member
Matthew
Join Date: Aug 2017
Posts: 28
Rep Power: 9 ![]() |
Quote:
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#5 | |
Member
Yousef
Join Date: Feb 2015
Posts: 40
Rep Power: 11 ![]() |
Quote:
Just search for inflow turbulence generator and you will find various methods and research on this. I also suggest that you familiarize yourself more with turbulence to get better idea about length scales. Without using those methods, my suggestion is to refine the grid in all directions and increase the intensity of inflow turbulence. Robert- you are also right the only dedicated solver for DNS in OpenFOAM is dnsFoam. But that is for decaying homogeneous isotropic turbulence. I believe other solvers can be used for DNS as long as: -there is no turbulence modeling -mesh requirements are met -proper schemes are used Regards, |
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