[hadiniesta]

Hi everyone who read this post,

I am currently looking for some guides to do the spray simulation using fluent because I am quite new in using fluent.

The main objective is that I want to get the DROPLET SIZE DISTRIBUTION or SMD, FUEL PENETRATION and SPRAY ANGLE of the fuel injector.

I've tried to do the simulation by referring to some of tutorials I got from the internet and fluent tutorial guides (Modelling Evaporating Spray). Here are the settings that I have used:

1. Geometry (Models)

Named selections: inlet, outlet, injector body, walls.

2. Meshing

Under 'Sizing' tab, I've made this change:

Use Advanced Size Fn: On:Proximity
Relevance Center: Coarse
Smoothing: High

Others are remained as Default.

3. Setup (Fluent)

Under 'General' tab: I've scaled up the mesh into millimeter (mm).

Under 'Models':
Models.PNG

For Discrete Phase Models, I enabled 'Interaction with Continuous Phase', 'Mean Values' and 'Unsteady Particle Tracking'. I set 'Number of Continuous Phase per DPM Iteration = 2' and changed 'Particle Time Step Size to 0.0001'.

In Tracking Parameters, I changed 'Max. No. of Steps' to 50000 and remained the value of 'Step Length Factor' as 5. I also enabled 'Breakup' option in Physical Models.

I've defined Injection for this simulation. Below are the injection properties that I used:

Injection type: surface (released from inlet)
Particle type: Droplet
Material: octane-liquid
Drag Law: dynamic-drag
Breakup model: TAB (Breakup Parcels = 50)
Parcel Released method: standard

In Point Properties, I set temperature to 293K, start time = 0s, stop time = 100s, VM = 80 m/s, total flow rate = 0.000428 kg/s and remained other properties and settings as Default. Meanwhile, the 'Inject using Face Normal Direction' and 'Enable Breakup' options are enabled.

Under 'BC': I made some changes in inlet and outlet zones only.
Inlet:
type: velocity-inlet

Outlet:
type: pressure-outlet

Under 'Solution Methods': I used SIMPLE scheme.
Under 'Solution Controls': URF are remained as Default.
Under 'Solution Initialization': I used Hybrid Initialization.

*noted that other settings/parameters that are not mentioned above are remained as Defaults.

After initializing and running the simulation until some iteration, I got the Divergence detected in AMG solver error (fatal error) and fluent had been closed directly.

I really messed up and don't know what else can be done to get this simulation running and produce the satisfactory results. I really hope that someone can give me the guidance regarding this simulation.

All the guidance would be appreciated. Thank you.

[AoJie]

Hello hadiniesta, have you solved your problem ?

I'm pretty new with FLUENT and I'm trying to solve a similar injection problem.

Did you mesh your geometry properly ? If you didn't it is possible that FLUENT is not able to set boundary conditions correctly.

Also I have a question: you said you used the "Modeling Evaporating Liquid Spray" tutorial, right? Did you find the associated geometry ? If yes could you send me a link, or maybe send me the file via email at ao.jie@outlook.com ? Because I've been unable to find it

Best regards

[SRI28337]

this seems bit complex geometry. you can make it simple for analysis. i guess the approach is pretty right one..
joe didi you get any answer ??