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-   -   Water Droplets Entrained within Airflow / Nasal Spray Simulation - Basic Beginner (https://www.cfd-online.com/Forums/fluent/200238-water-droplets-entrained-within-airflow-nasal-spray-simulation-basic-beginner.html)

AllyB2106 March 27, 2018 20:31

Water Droplets Entrained within Airflow / Nasal Spray Simulation - Basic Beginner
 
Hi there,

I am relatively new to ANSYS, with a fairly basic module undertaken in university. For my final year project, I am trying to model aerosol droplets (equivalent to water droplets) in an air flow of 3 litres/min entering the nasal cavity, of which I have approximated as a Y shaped tube.

I am using ANSYS FLUENT version 19.0 (student version).

Have been following tutorials from youtube but they are not exactly what I am looking for.

So far I have the following setup:

(Opened via double precision serial)

General: Pressure based - type solver with gravity enabled (9.81/ms^-22) and transiet

Models:
Viscous Laminar model with realizable k-epsilon (2 eqns) and enhanced wall treatment (have also tried scalable wall functions and standard)

Discrete Phase is on with interaction with continuous flow enabled and Max number of tracking steps is 50000 (have altered this as I kept getting incomplete particles - this did not make a difference so it must be something else). I have enabled unsteady particle tracking and injecting particles at a particle time step of 0.001s. I have enabled the pressure gradient force, automated tracking scheme, linearized source terms and accuracy control.

The injection is a surface injection at the inlet, I chose a roisin rammler distribution with 5 micron diameter mean sized particles, mass flow rate of 0.05 kg/s and velocity of 0.2 m/s. Have injected using face normal direction. Have also enabled random walk model under turbulent dispersion and random eddy lifetime. I said the stop time was 1000s.

I basically need the aerosol to come in via the two inlets (which have been named accordingly). Both the inlet and outlet have been assigned "escape" under DPM boundary conditions and the walls are assigned with "trap".

What I need from this simulation is to assess how many particles deposit within the airways i.e. number of droplets in versus number out. I also would like to see how they break up via the TAB model - have tried this also to no avail. I cannot seem to get any particle tracklines - however the streamlines come out fine.

I would really really appreciate any input or feedback, as this is my first time doing this complexity of simulation - have very little experience and have spent 9 hours on this to no fruition. If someone could just provide me with some guidance on this configuration or a basis configuration for particle deposition along the walls and particle breakup, I would be really grateful.

Best wishes,

Allison.


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