hai

In my problem for non-premixed combustion, I am sending coal by using "release from surfaces" option and taking coal inlet as the surface....now, what boundary condition shall I give for coal inlet in boundary conditions panel..."only coal is sent throught the coal inlet"///

air is coming from other inlet....

waiting for a kind response

Prasanth

hi,

from my point of view you can use mass flow inlet as a boundary condition for coal.

let me know if this helps

regards

David

hai

Thanks for your kind reply. I have given mass flow condition itself. I want to know which is reasonable: 'trap' or 'escape'.

thanks and regards

Also I want to know what we have to specify for mean mixture fraction and variance>??

thanks in advance prasanth

I think trap means incomplete,escape means particle flow with fluid out of boundary

Hello Sir

Thanx for your reply. But still we are having doubt with it. whether escape mode escapes out all the particles when it approaches the inlet/outlet boundary? If we don't want the particle to escape through some inlet/outlet, what type we have to select: "escape" or "trap"? when will we use the other mode "wall jet" (application?)?

In defining discrete phase, we will specify velocity and flow rate for coal; is it needed to specify the mass flow rate at the mass flow inlet B C at coal-inlet?

* In our case, at coal inlet,only coal goes into the chamber, not along with air. Air comes through other inlet.

Regards Prasanth

I am sorry,I dcannot reply this question.In my cases particles come in with fluid.

I think in fluent6.1'Tutorial 13: Using the Non-Premixed Combustion Model may give you some help.

They also doing same thing as yours.

thank you sir

hi,

this is what FLuent's manual says:

``trap'' terminates the trajectory calculations and records the fate of the particle as ``trapped''. In the case of evaporating droplets, their entire mass instantaneously passes into the vapor phase and enters the cell adjacent to the boundary

``reflect'' rebounds the particle off the boundary in question with a change in its momentum as defined by the coefficient of restitution

``escape'' reports the particle as having ``escaped'' when it encounters the boundary in question. Trajectory calculations are terminated

``wall-jet'' means that the direction and velocity of the droplet particles are given by the resulting momentum flux, which is a function of the impingement angle, $\phi$, and Weber number.

I didn't know wall jet. I think it is a new BC included into DPM in fluent.

FLUENT assumes the following boundary conditions:

* ``reflect'' at wall, symmetry, and axis boundaries, with both coefficients of restitution equal to 1.0

* ``escape'' at all flow boundaries (pressure and velocity inlets, pressure outlets, etc.)

* ``interior'' at all internal boundaries (radiator, porous jump, etc.)

I hope this helps

regards

David