-11......0.003800$$ablacdot（rhothbf{u}otisthbf{u}）=-thbf{T}{ext{asy}+abla^2thbf{u}+thbf{F}{ext{fil}$$11111537%20%-110.8%0.3%0.231%......0.04%...............11119...15161711-300011.........-317