ANSYS FLUENT: DPM Simulation - Wall Impingement Pressure

Hi everyone, I am doing a spray simulation with DPM. After getting the flow with VOF, I am injecting particles at breakup length. Those droplets go and hit a plate. I am trying to compare the pressure on the wall with experimental results.

I am using the default static pressure calculation at the wall in FLUENT. Does this take into account for the pressure exerted by droplets impinging on the wall?

My calculated values are around 10 Pa and experimental values are around 20000 Pa. So there is something really wrong going on. Either its my droplet size and number or the way I am calculating the pressure.

Would anyone like to suggest a better method for calculation of pressure exerted by the droplets on the wall?

Note: I am assuming that after breakup of the initial spray only droplets exist. Do I also need to enter a water inlet along with the droplets?

Attached images of the particle tracks and pressure distribution on the plate after 700 iterations with a time step of 0.0004 sec.


Comments

  • RobRob UKForum Coordinator

    Have a look in the DPM Variables too, there are force plots available.

  • Thanks for your comment Rob.

    Yes, that would have been great. For some reason, both the X and Y force plot as well as the normal pressure plot is zero at all points.

    Do you know why this might be the case?

  • RobRob UKForum Coordinator

    Do you have a wall & wall:shadow pair?

  • No I do not have any wall shadows. I am only modelling the fluid zone in 2D.

    Here, 'plate' is the only wall. 'sidewalls', 'topwall' and 'inlet' are set to pressure-outlet.

    DPM Droplet particles are injected about a cm away from the inlet/topwall. The plate is at 1500 K and wall-film DPM BC is enabled.

  • RobRob UKForum Coordinator

    DPM is coupled?

  • I am not sure what you mean by a coupled DPM.

    Its not a VOF to DPM simulation since that is only available in 3D. I ran VOF separately and am now running DPM separately.

    I have the species transport model enabled in addition to DPM if that's what you are asking. This is enabled to account for droplet evaporation at the plate. Plate has 'wall-film' DPM boundary condition.

    Energy equation is also enabled. And realizable k-ε turbulence model is being used with standard wall functions.

  • I realized you probably meant if the interaction between the continuous and discrete phase was enabled. Yes, this is enabled and DPM iteration interval is set to 10.

  • RobRob UKForum Coordinator

    Try without the wall film, I can't remember what that does to the reporting as technically the particles may hit the film rather than the wall once it's formed.

Sign In or Register to comment.