I'm simulating the dissolving process of a sphere like droplet in another liquid. The droplet it composed of S and P.
S can dissove into the out phase liquid W, while P cannot and stay in the droplet. The droplet surface(S&P-W) is shrinking with time. The problem is a transient one.
The governing equation is Fick's second law. Because of the symmetry, the problem can be describled by a 1 D transient equation.
I set a 1D model with ALE to solve it.The surface moves at a speed of dR/dt. In initial, I encountered minus concentration problem because the sharp concentration gradient near the boundary. Then I found that the Heaviside Function can be apllied to conquer this. However , another problem comes. The concentration should be in the range[0,1], I got jumping profile, wich shows that Cs sometimes higher than 1, which is not the case obviously.
Would you please give me some suggestions?
Appreciation!
Best Regards!
Tsong
S can dissove into the out phase liquid W, while P cannot and stay in the droplet. The droplet surface(S&P-W) is shrinking with time. The problem is a transient one.
The governing equation is Fick's second law. Because of the symmetry, the problem can be describled by a 1 D transient equation.
I set a 1D model with ALE to solve it.The surface moves at a speed of dR/dt. In initial, I encountered minus concentration problem because the sharp concentration gradient near the boundary. Then I found that the Heaviside Function can be apllied to conquer this. However , another problem comes. The concentration should be in the range[0,1], I got jumping profile, wich shows that Cs sometimes higher than 1, which is not the case obviously.
Would you please give me some suggestions?
Appreciation!
Best Regards!
Tsong