| Author | Message | |||
     Jack Zhang (lovekk) Member Username: lovekk Post Number: 7 Registered: 01-2007 |
Nelson: I'm analyzing a rainfall infiltration into slope problem with the governing equation as follows: dx(kx*dx(uw/gw+y)) + dy(ky*dy(uw/gw+y)) =mw2*dt(ua-uw) where kx,ky: permeability in x, y direction wu:pore water pressure(kind of energy) ua:air pressure mw2: a variable which is a function of (ua-uw). The problem is sketched in the Fig.1 attached.In Fig.1, the line ABCD represents the slope boundary, q means the rainfall intensity(flux). Also plotted is the coordinate system used in the analysis. I have two problems at present which seems to be typical (1)In bounday AB, CD, the flux can be specified using the "natural" command. How about the flux boundary condition along BC? in this case the flux is not perpendicular to the boundary.Shall i use the combination of NORMAL and TANGENTIAL to specify the flux? (2) My boundary conditon also varies with time, as indicated in Fig.1. How can i treat such time variant boundary? Thank you for your attention.
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| Jack Zhang (lovekk) Member Username: lovekk Post Number: 8 Registered: 01-2007 |
Nelson: For the 2nd problem, i think i can realize it via the "table" command. But for the 1st one, i am still wondering... | |||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 761 Registered: 06-2003 |
1) The rain may fall downward, but only the normal flux enters the soil. The tangential part by definition runs off. If you want all the rain to soak in, put it all in the normal component. Note also that the meaning of the Natural BC is the surface-normal component of the vector [(kx*dx(uw/gw+y)), ky*dy(uw/gw+y))] 2) A TABLE will do it. You can also modify the TABLE with SMOOTH or BLOCK. See "TABLE input" in the Help Index. | |||
| Jack Zhang (lovekk) Member Username: lovekk Post Number: 9 Registered: 01-2007 |
Nelson: thank you. btw, are you aware any examples that analyze pile group using flexpde? | |||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 763 Registered: 06-2003 |
I am not aware of any, but then most users don't tell us what they are using FlexPDE for.... |
rainfall infiltration into slope