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Franz October 20, 2008 08:35

Simulation of airflow through round bales/crops
Hi, for my research I need to simulate de airflow through round bales and also through a bed of other products like plant leaves (my research is about drying of these products). I have no experience with CFD and only know about FLUENT. Is FLUENT the right choice to do the job or are there other more adequate and or cheaper softwares? We still have to buy the software. Also, from reading in FLUENTīs used guide, I see that to simulate the flow through a perforated plate one can use the porous media model. However, is it possible or correct, to simulate this flow by creating the dryer geometry including the perforated plate? Thanks a lot.

mettler October 20, 2008 09:43

Re: Simulation of airflow through round bales/crop
I would not recommend using porous media to model flow through a perforated plate, unless you are modeling a stack of plates (matrix heat exchanger). Look for the authors Sparrow, Venkatarathnam and later Hayes on modeling a perforated plate.

When using Fluent's porous media model there are things that have to be known that can only be known through laboratory experiments (the inertia and permeability coefficients). If you can find good estimates for those values for your experiment you will be in good shape. But, if you can't then you will have to run an experiment yourself. Getting the coefficients from experimental data is pretty easy, but designing and running the experiment is a hassle.

tom October 20, 2008 17:50

Re: Simulation of airflow through round bales/crop
I think the porous media assumption is fine for your case. Will you be be doing some wind tunnel modelling to relate pressure pressure drop to the inertia and viscous coeffs? If not I think there is a paper by Carpenter (can't rem. 1st name) in Journal of Agricultural Engineering Research for some agricultural materials. As regards software, I think fluent should be good, and it will come in the Ansys workbench soon, so should be even more user friendly.

Franz October 22, 2008 03:59

Re: Simulation of airflow through round bales/crop
Thanks for answering. Yes, I guess if I donīt find any useful data already in the literature, I will make some experiments to relate pressure drop to the resistance coefficients. I will look for the paper you mention. I think for the round bale I have to find the coefficients for each direction, donīt know however if I can use the Cartesian coordinate system or I definitely have to use the cylindrical system. Any thoughts? Thanks!

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