Search found 84 matches

by zhubq
Wed Apr 27, 2011 9:49 pm
Forum: pre-processing
Topic: The role of the phase minimum (phMin)
Replies: 6
Views: 2911

Re: The role of the phase minimum (phMin)

HI, Bernd. Thanks。 Is this right: \phi_\alpha^*=MIN(\phi_\alpha,\%200.01) not \phi_\alpha^*=MAX(\phi_\alpha,\%200.01) ? When I ran a simulation of cementite precipitation from austenite in 1D, I found that the driving force decreases across the interface from austenite side to cementite side. The ca...
by zhubq
Wed Apr 27, 2011 8:05 pm
Forum: recrystallisation/grain growth
Topic: Mobility for austenite grain growth
Replies: 11
Views: 7392

Re: Mobility for austenite grain growth

Hi, Great to see that discussion is now starting between users of the MICRESS forum! @zhubq: bottle of champaign next time we meet! @all: use the "subsribe forum" button at the bottom of the page in each subforum to get email notice of new answers or threads! admin @admin: I will do more and better...
by zhubq
Wed Apr 27, 2011 7:52 pm
Forum: recrystallisation/grain growth
Topic: Mobility for austenite grain growth
Replies: 11
Views: 7392

Re: Mobility for austenite grain growth

Hi zhubq, thanks a lot for your comments. I understand that when the mobility is increased, the grain growth happens more intensively. And MICRESS has to solved the equations more due to this interaction. That's why it takes much longer?? nokkikku Yes, because for each time step, the interface can ...
by zhubq
Wed Apr 27, 2011 7:42 pm
Forum: pre-processing
Topic: The role of the phase minimum (phMin)
Replies: 6
Views: 2911

Re: The role of the phase minimum (phMin)

Hi, Bernd. From the \Delta t equation above, if \beta is stoichoi phase, m_\beta is infinite,then \Delta t \propto 1/(1-\phi_\alpha) . So there will be a lower bound of \Delta t when \phi_\alpha =0 . By the way, do you mean now PhiMin does not affect the time step in MICRESS [new version?]? I am usi...
by zhubq
Wed Apr 27, 2011 8:00 am
Forum: recrystallisation/grain growth
Topic: Mobility for austenite grain growth
Replies: 11
Views: 7392

Re: Mobility for austenite grain growth

Hi, there. I think mobility is quite undeterministic. The values from literature are in a large range. You'd better fit it with your own experimental data. High mobility means high velocity of the interface. therefore, you have to decrease the time step (done by MICRESS automatically) thus more iter...
by zhubq
Wed Apr 27, 2011 4:02 am
Forum: pre-processing
Topic: The role of the phase minimum (phMin)
Replies: 6
Views: 2911

Re: The role of the phase minimum (phMin)

Hi, Jan
Based on the formula given in another thread (see below), the phMin is not involved in the time step.
Image
by zhubq
Wed Apr 06, 2011 9:27 pm
Forum: phase-field model
Topic: diffusion problem
Replies: 6
Views: 2985

Re: diffusion problem

Hi, Bernd.
Thank you. Now I know it. A numerical trick has to be used to enforce the pair-wise flux to be 0 if the neighbor has a zero value of order parameter.
by zhubq
Wed Apr 06, 2011 7:27 pm
Forum: phase-field model
Topic: diffusion problem
Replies: 6
Views: 2985

Re: diffusion problem

if \phi_i >0 and \phi_{i-1}=0, how to calculate \nabla c in between?
by zhubq
Wed Apr 06, 2011 6:59 pm
Forum: phase-field model
Topic: diffusion problem
Replies: 6
Views: 2985

Re: diffusion problem

Hi, Bernd. I am not sure whether my understanding is right. First of all, you get the values of D_\alpha \phi_\alpha \nabla c_\alpha e.g. (Y(i-0.5) and Y(i+0.5)) between each two grid points e.g. X(i-1), X(i) and X(i), X(i+1). Then you use the two values ((Y(i-0.5) and Y(i+0.5))to get \nabla(D_\alph...
by zhubq
Wed Apr 06, 2011 1:07 am
Forum: phase-field model
Topic: diffusion problem
Replies: 6
Views: 2985

diffusion problem

Hi, Bernd. when solving the diffusion equation in the interface, how does MICRESS calculate the gradient of the concentration at the edge of the interface? Because if the point is at the edge, we have to use the points out of the interface to calculate the gradient \nabla {c_i} . For phase field equ...