Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Reactions with non-integer exponents
Posted 2017年2月15日 GMT-5 06:36 Chemical Reaction Engineering Version 5.1 1 Reply
Please login with a confirmed email address before reporting spam
I am using the transport of diluted species physics (let's call it species "c") and have stumbled across a problem that is driving me up the wall. I have the diffusion equation being applied to a 3D geometry but there is also a REACTION part to my model, which I added to the physics and gave a reaction rate. Within the reaction rate I am using a non-integer exponent for example: -c^(2/3).
Now, when I do this COMSOL tries to apply this power to negative values and so my question is this: is there a way to tell COMSOL that if it comes across a negative value, to just treat it as zero? I.e if c<0 then make c=0.
I am slowly going mad, help me Obi-Wan Kenobi!
David
Now, when I do this COMSOL tries to apply this power to negative values and so my question is this: is there a way to tell COMSOL that if it comes across a negative value, to just treat it as zero? I.e if c<0 then make c=0.
I am slowly going mad, help me Obi-Wan Kenobi!
David
1 Reply Last Post 2017年2月16日 GMT-5 05:43
Please login with a confirmed email address before reporting spam
Posted:
8 years ago
I suggest that instead of writing c^(2/3), write (max(eps,c))^(2/3). I cannot guarantee that it works 100% but please try.
eps is a machine constant, a very small positive number.
BR
Lasse
eps is a machine constant, a very small positive number.
BR
Lasse