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How dose COMSOL V3.5 treat these two coulped PDEs ?
Posted Oct 1, 2010, 8:07 a.m. EDT 0 Replies
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I am comfused about how the following PDEs can be implemented in COMSOL v3.5 correctly:
Modeling domain: 1D
Dependent variables: u1 and u2
PDEs:
Dependent variable: u1
Governing equation for u1:
d[-K*f(u1,u2)*(du1/dx)]/dx=S_u1
which is a stationary, coupled with u2, and second-order PDE
Its BCs:
at left point: -K*f(u1,u2)*du1/dx|(at x=0)=G_in_t. here the G_t_in is a fixed value
at right point: u1|(at x=1)=p_out p_out is also a fixed value
Dependent variable: u2
Governing equation for u2:
du2/dt+ d[-K*u2*(du1/dx)]/dx=S_u2
which is a dynamic, coupled with u1, and first-order PDE
Its BCs:
at left point: -K*u2*du1/dx|(at x=0) =G_in_v G_in_v is fixed value
Note:
1) K, S_u1 and S_u2 are constant.
2) f(u1, u2) represents a linear relationship function.
e.g. f(u1,u2)=a*u1+b*u2
3) -K*f(u1,u2)*du1/dx means the mass flux physically
4) -K*u2*du1/dx means the mass flux physically
My solution: I used "general PDE" application mode to model these two PDEs in COMSOL 3.5. As for the u1, it needs two BCs to enclose the problem; As for u2, it needs one BC therocally, but in COMSOL it still exists a block to be filled at the right point.
How could I implement these two PDEs in COMSOL v3.5 correctly and solve them successfully?
Thank you for your attentation !
Hello Guangji Ji
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