Fluids

How to get mass flow rate data of the particles in transient Discrete Phase Model (DPM)

• sandeepjaggarapu
Subscriber

Hello Ansys Community,

I am solving a DPM steady state as well as unsteady state simulation with unsteady particle tracking of lubricating-oil with the unsteady continuous fluid as air.

I am trying to simulate a two-phase flow(air and oil) in a circular pipe (Dia. 5mm and length 20mm) using DPM. Can anyone please address the following problem?

1. I have extracted the particle data (reports -> Discrete Phase -> sample -> outlet) both in a steady and transient state. The main aim of this simulation is to get the mass flow rate of the particles at the outlet. I got the mass flow rate results for the respective particle size is obtained. But in the case of transient state simulation, the mass flow rate data is not getting saved.
2. From the console panel, it shows that the particles trapped were 137 out of the injected 20k particles. Is it possible to get data on the different sizes of particles that are trapped on the wall? If yes, can you suggest a solution on how to obtain the data?

Here is my setup:

Gravity-> Y: -9.81 m/s^2

Viscous-> Laminar

Discrete Phase (uncoupled and no forces are added except drag force)

Discrete phase on (rosin rammler particle distribution with surface injection)

Boundary Conditions: Inlet & outlet DPM: escape

Wall DPM: trap

Methods -> Simple

Residuals -> 1e-6

Initialize: Standard

Run Calculation: No. of iterations: 1000

Time -> Transient (The same procedure as that of steady but the transient conditions were considered)

DPM (uncoupled and no forces are added except drag force)

Type-> Fixed

Number of Time Steps: 1000

Time Step Size: 1e-5

Max Iterations: 20

Reporting interval: 1

Profile update interval: 1

I have attached the picture of the sample data collected.

• Surya Deb
Ansys Employee
• sandeepjaggarapu
Subscriber
Hello,Thank you for your reply. nSir, do you know any UDF that writes the sampling trajectories data? So that I could edit that.n
• Surya Deb
Ansys Employee
Hello, nYou could try using DEFINE_DPM_OUTPUT UDF to write out particle data when it crosses a sample plane or surface. You can also add levels of customization to this UDF for your purpose. You will find more information here.nI hope this helps.nRegards,nSDn
• ai0013
Subscriber
Fluent has a built in option to sample particles from a surface. What comes to my mind is to select your outlet as sampling surface. In transient, click start and continue simulating. Once that you ran your case sufficiently long, click stop and post process your data.