Why no "Concentration source" like "Heat Source"?

Thread index  |  Previous thread  |  Next thread  |  Start a new discussion

RSS FeedRSS feed   |   Email notificationsTurn on email notifications   |   7 Replies   Last post: October 9, 2013 1:32am UTC
Lokesh Patil

Lokesh Patil

October 7, 2013 3:37am UTC

Why no "Concentration source" like "Heat Source"?

I have been working on 4.2 and getting a grip on its interface since I have worked on 3.5 and other softwares before. I basically have a number of micropheres loaded with a drug. And these microspheres which are embedded inside a hydrogel and are slowly releasing the loaded drug. I want to assign these microspheres with a concentration that would vary as f(t).

I thought I could just assign the concentration of these micropsphere domains with the equation f(t), but apparently there is only option for a boundary concentration which I am not quite understanding (since I am getting wrong results with boundary concentration lol). Heat equation is essentially same as simple diffusion equation. Shouldn't the methods be same?

Would really appreciate if someone could shed some light on this.

Reply  |  Reply with Quote  |  Send private message  |  Report Abuse

Tero Hietanen

Tero Hietanen

October 7, 2013 5:19am UTC in response to Lokesh Patil

Re: Why no "Concentration source" like "Heat Source"?

Hi,

Source what you looking for is "Species Source". I don't is this in version 4.2 but version 4.3b has it.

www.comsol.com/products/specif...ns/chemical-species-transport/

Best regards

Tero Hietanen

Reply  |  Reply with Quote  |  Send private message  |  Report Abuse

Lokesh Patil

Lokesh Patil

October 7, 2013 7:05am UTC in response to Tero Hietanen

Re: Why no "Concentration source" like "Heat Source"?

Thanks Tero. :)
But since I do not have access to 4.3b right now, is their a workaround this? I thought if I could assign the boundaries of sphere with variable flux, that might work. But apparently flux cannot be applied to interior boundaries.

Reply  |  Reply with Quote  |  Send private message  |  Report Abuse

Tero Hietanen

Tero Hietanen

October 7, 2013 7:22am UTC in response to Lokesh Patil

Re: Why no "Concentration source" like "Heat Source"?

Hi,

Sorry, I don't know how to do this other way.... I have also try to found solution this (I don't have Chemical engineering module and CFD module doesn't include this) but I haven't found any good way to go around problem.

Best regards

Tero

Reply  |  Reply with Quote  |  Send private message  |  Report Abuse

Jesus Lucio

Jesus Lucio

October 7, 2013 10:11am UTC in response to Lokesh Patil

Re: Why no "Concentration source" like "Heat Source"?

Hi,
It seems that the source term (the "species source" you want) is just the "Reactions" node, with which you can represent creation or destruction of the related species. It's present in raw COMSOL Multiphysics, for that you don't need additional Modules (or if you use that Chemical Reaction Eng. Module you'll have that feature for sure).
Regards,
Jesus.

Reply  |  Reply with Quote  |  Send private message  |  Report Abuse

Lokesh Patil

Lokesh Patil

October 7, 2013 5:16pm UTC in response to Jesus Lucio

Re: Why no "Concentration source" like "Heat Source"?

Hi Jesus,

I actually did think of that two. But isn't the reactions term made for only consumption or production? In a sense that if chemical A reacts with Chemical B to produce the species c. In my model the only thing that is happening is controlled release of drug from the microsphere into the hydrogel. So the total amount of drug in the system is same.

Although I am going to try this once more. The term "reaction" is just confusion to me lol.

Reply  |  Reply with Quote  |  Send private message  |  Report Abuse

Jesus Lucio

Jesus Lucio

October 7, 2013 5:37pm UTC in response to Lokesh Patil

Re: Why no "Concentration source" like "Heat Source"?

Hi, Lokesh,

I had understood that you only wanted to simulate your species (drug) concentration and that the microspheres were not included in the geometry. Do you intend to include them? If so, their interior could be out of physics (diffusion), and their surfaces would then be external boundaries of the main geometry. But the prefix *micro* suggests that they are too small to take them into account in the geometry. In that case, you could simulate them simply by the drug delivering rate: f(t), if their effect is homogenous, or f(x, y, ..., t) if that drug-delivering is also a function of the position. You know where those micro-spheres are located, and how to spatially model their drug-delivering.

Jesus.

Reply  |  Reply with Quote  |  Send private message  |  Report Abuse

Lokesh Patil

Lokesh Patil

October 9, 2013 1:32am UTC in response to Jesus Lucio

Re: Why no "Concentration source" like "Heat Source"?

Hi jesus,

Thanks a lot!
You are actually right. The reaction term can be simply used as a source. I went back to comsol and stared at the equation for 10 minutes and realized I do not need a new "concentration source" term. I can simply specify it in the "reactions".

And about the microspheres, I am actually including them in the model. I will again run the simulation using the reactions term for these spheres and see results.

Reply  |  Reply with Quote  |  Send private message  |  Report Abuse


Rules and guidelines