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 micpage18 January 29, 2007 14:18

Hi, I want to simulate a i

Hi,

I want to simulate a iron hopper.

The hopper is like a silo with a cone shape full of iron ball (2 cm of diameter). The silo is emptied by gravity.

I want to know what is the "flow rate" of iron ball.

Is Openfoam can simulate a case like this?

Thank you

Michael Page

 alberto January 29, 2007 19:38

Hoppers discharge of fine powd

Hoppers discharge of fine powders (up to 1mm; yours are not exactly "particles" :-)) is commonly simulated using a two-fluid model. The properties of the granular phase can be described:

a) using the kinetic theory of granular flow, together with a frictional stress model (see Schaeffer, Johnson and Jackson, Srivastava and Sundaresan), which is essential to properly capture the flow field properties in the densest zones.

This approach was applied in a recent paper from Srivastava A., Sundaresan, S., Analysis of a frictional&ndash;kinetic model for gas&ndash;particle flow, Powder Technology 129 (2003) 72&ndash; 85, using MFIX ( www.mfix.org ).

b) using a specific rheological model.

OpenFOAM currently implements the kinetic theory of granular flow in twoPhaseEulerFoam and some frictional models. Unfortunately the solution of dense flows like those in hoppers is still not fully stable and some more work is necessary (and welcome ;-)).
The same solver implements a simple rheological model (see Gidaspow and others authors, look for "normal stress modulus"), which is more stable.

c) A more computationally expensive method is based on Discrete Element Simulations. But I don't have much experience with it.

For the first two approaches, I've some doubt due to the size of the spheres.