Learning Forum

[fluent4society]

I am simulating a room with a person in fluent. The room has an air inlet (boundary) and outlet(pressue outlet boundary). My aim is to find the number of particles (coming out of person's mouth) leaving the room when person talks. For this, i defined the periodic mass flow inlet boundary condition at the person's mouth to mimic the breathing rate ( 3.5 cfm) . Also, i am trying to use DPM for particle (water vapour) generation near person mouth. I want to generate a particle concentration of 100/cm^3 for every timestep 0.01 s and then track them. I tried to find the concentration option in injection tab, but could not find it. nIs there an option to give particle concentration as input ? n

[Rob]

No, for DPM it's an injection mass flow rate. n

[fluent4society]

Thank you. Do you mean i can only give mass flow rate ? Is there any way i can use the concentration directly in fluent ? n

[Rob]

Correct. Fluent can report the concentration if you're running a coupled DPM solution. The other multiphase models use a mass fraction definition on the inlets, but I'd not advise using those here. n

[cfdexplorer]

I know the diameter of each water-liquid particle and velocity of particle. Also, i know the number of particles. I know that mass flow rate = density*area*velocity. But, where do i enter the number of particles in DPM injections ??? Is it in parcel tab ?? Thank you in advance n

[Rob]

We inject a number of parcels into the domain. Given the size of the particles and their mass flow it's not practical to model every particle. The number of streams (parcels) is set in the injection, and will depend on which injection type you're using. You can increase the number of parcels by using stochasitc tracking too (turbulent tab in the injection). n