Learning Forum

[pcmac]

May I request some assistance in performing a model validation using the mass fraction, similar to this related literature?

Should I activate the species transport? My study is all about a modification in the sedimentation tank to observe its settling efficiency. As part, I want to perform this mass fraction validation (effluent) but I can't seem to find an option for how I can observe this.

Thanks in advance.

[Rob]

Species mixture density works on a cell & mixture basis so you won't see any separation. The multiphase models will allow sedimentation but the number of phases needed may be high (one phase per particle size). As an added bonus the settling velocity will be low (you need to do some reading on Stoke's Law) but the flow time step may be small relative to the overall sedimentation time. 

What is the purpose of the model beyond trying to replicate an experiment? 

[pcmac]

Concerning the multiphase model, I only activated DPM using injections per mean particle diameter. May I know if that will correspond to my objective of observing the settling efficiency of the tank?

Solely, it’s for replicating the experiment and using the given mass fractions. 

Can you suggest another method on how I can validate my current investigation?

 

[Rob]

DPM has a volume fraction limit, so tends not to be suitable for sedimenter modelling where the volume fraction can be high (and become compacted) in the sludge layer. 

However, if the intent is to check for sediment removal DPM may be suitable as you simply look for how much of a given size is carried over. 

[pcmac]

I see. Regarding the validation of my current investigation, may I know how can I activate/use mass fraction?

[Rob]

With DPM you don't, but you can monitor escaped mass and work it out relative to the water overflow. 

 

[pcmac]

For follow-up, is there a way I can also include the floc concentration vs. position in my report using only the DPM? I am trying to illustrate how my modifications alter the tank's settling capabilities, and including this plot will further support my claim.

[Rob]

You can use the DPM out files to report what hits where, otherwise you may need to use a more appropriate model.