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Fatnes August 21, 2009 15:36

Bed lifting
 
Hi.

I have a horizontal pipe with a 90 degree pointing upwards. I have a case where I'm suppose to study the behaviour of dispersed hydrate particles. What I want to do is to place a bed (of a specific height according to experiments) of particles in the horizontal test section and inject a continuous fluid at low velocities.

According to experiments the particle concentration in the bed is 0.535, maximal bed height 1.86cm and water inlet velocity 0.05 - 0.35m/s. I want to use the Krieger-Dougherty equation for the viscosity. I assume that the flow velocity is zero on the infinity far from the inlet because the bed is also there. So the injection of fluid has to be manage to be non-uniform in some kind of way..? I also assume that at low flow rates the lifted particles are completely settled in the deep part so the dispersed phase concentration at the inlet is zero.

I expect to see that some particles will be pushed to the bend. I then want to calculate the average bed height from the model and compare to experimental data.

My first query is to how to set the particle height and concentration in the horizontal section as explained above (I have not found anything special in "Pre Help" about to insert an initial particle bed)?

ghorrocks August 22, 2009 06:00

Hi,

I assume you are trying to do something similar to a fluidised bed simulation. CFX has models for this. It is primarily developed for coal combustion but I have seen it adapted to other purposes.

This is quite a tricky area to get accurate results. I don't think there are tutorial examples on fluidised bed flows (worth checking, I might be wrong) otherwise talk to your CFX support person as they can probably get some demo examples.

Glenn


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