[apo]

Hello to every one,

I can't understand at "set injection properties" why we have to set both of velocity magnitude and total flow rate? Can anyone explain me what exactly are these variables?

[edoan]

the velocity magnitude is the velocity the particles will have as they enter the domain. the flow rate is the mass flow of particles you wish to model. DPM does not solve for every single particle but uses one particle that can be representative of many therefore you need to input the total mass flow.

[apo]

Thank you very much for your answer!
But i know that m[kg/s] = v[m/s]*A[m^2]*ρ[kg/m^3]. So I have to know A[m^2] to find a relation between m and v or i can set any value i want? Also, can I set v=0 m/s ?

[edoan]

if you set the particle velocity to 0 the particles will be accelerated by the flow from rest to their terminal velocity this will cause a pressure drop in the fluid as the fluid has to lend its energy to the particles to accelerate them if you dont want this then give initial velocity close to terminal velocity. the mass flow of particles should be known.. if you would like to give me a description of your case i can give you my advise

[apo]

i have a boiler and i want a combustion of solid particles of coal (coal-mv). The flow rate of the case is 0,2 kg/s and total number of streams 20. I have a primary and a secondary stream of air. how can i set this flow rate at "Set Injections Properties"? I have set this at the total flow rate and at the tab of results the "particle mass source" appears to be much lower in the domain of injection.
also i don't want the particles to be accelerated from the air. Have you any idea about this case?
Tell me if you want other information of the case.

thanks

[edoan]

Set the initial particle velocity to the avg velocity of the air near the injection area this will minimize particle acceleration. the mass flow you set in the injectin settings is the effective mass flow of the DPM particles im not sure why its not showing you that.