hi
i work at modeling of thermoacoustic phenomenon in rijke tube with ansys fluent
i want to show pressure oscillation in this phenomenon
i modeled a tube with 1m length and include just one segment of heat convertor
then i run steady-state solution with p(inlet)=0.5 and p(outlet)=0
and wall temprature (tempratue of heat convertor)=3000k
and when this solution convergenced next step is imposed pressure pulse at outlet such as p=30sin(2*pi*f*t) with udf for 2000 time step with time step 1e-5
and then change pout=0 and run transient solution for 100000 time step with time step=1e-5
i cant see any oscillation in pressure
anyone can help me?
thanks
Dear Hamid,
In general, it is not that easy to capture instabilities in the form of pressure oscillations using CFD.
You need to use compressible solvers with time steps small enough to capture propagation of sound waves.
This means that you should use density based solver in Fluent and calculate the speed of sound in your hot region and depending on your grid size, choose a suitable time step. It will usually be in the order of a few e-7. 1e-5 is definitely too large to capture acoustics.
Take a look at the attached article.
Article Prediction of thermoacoustic instability in Rijke tube using...
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