Learning Forum

[skimura]

Hello

I would like to perform evaporation calculations using the VOF model and reaction calculations using CHEMKIN-CFD simultaneously in Fluent.

However, when the multiphase flow model is turned on, CHEMKIN-CFD cannot be selected in the Speciation Model Settings window.

How can I solve this problem? Please help me.

I'm writing this using a translator.

 

[Rob]

Have a look at the Eulerian Multiphase model. You may need to model the chemistry using the built in models, not all of the Chemkin functions work with all of the Fluent models (yet). 

[skimura]

Dear Rob san

Thank you for your reply.

The Eulerian Multiphase model requires the input of constants for the reaction equation, which can be difficult.

Is there an easier way to read the CHEMKIN format?

 

[Rob]

I suspect it's a little more complicated as single phase reactions are mixture/kinetics limited but multiphase potentially adds vaporisation/evaporation to the list.  A colleague uses bits of Chemkin, but not multiphase so I'll see if he knows more. 

[Ren]

Hello, Shin,

If you wanted to set up the reactions by importing a Chemkin mechanism instead of manually entering the reactions, you can import the mechanism using the following command:

File->Import->CHEMKIN Mechanism...

After this, the mixture material will become available for the phases.

The Chemkin-CFD chemistry solver is not available for multiphase problems.

 

[skimura]

I'm sorry, bad question.

I would like to place a droplet in a gas and calculate how the droplet evaporates and mixes with the surrounding gas, causing auto-ignition.

For this purpose, I want to calculate evaporation and reaction at the same time.

The center of the image is the droplet and the surrounding area is the gas.

[Rob]

That's really not simple. Leaving the reactions aside (Ren knows a lot more than I do), the evaporation rate is linked to the combustion (heat release) in a feed back loop. For evaporation you'll also want to read up on the Eulerian model, VOF isn't currently suitable for this. 

[Ren]

Hello, Shin,

what is the diameter of the droplet?

For the gaseous reactions including autoignition, what you need is a reaction mechanism that also includes ignition kinetics and the finite-rate combusiton model.

[skimura]

Hello, Ren,

The droplet diameter is 100µm. I would like to reduce the droplet diameter to about 10 µm.

[Ren]

Hello, Shin,

For small droplets like this you can use the Discrete Phase Model (DPM) to model the droplet evaporation together with gaseous combustion/reactions. Please take a look at the user guide on DPM. 

[skimura]

Hello, Ren,

Thank you for your reply.
I will look into the use of DPM.