浩渺烟朦_
浩渺烟朦_
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大佬们, 一个复杂的偏微分方程求不出来, 望大佬们解答~~ miu0 = 4*pi*10^(-7); miur = 2000; S0 = pi*(0.25*10^(-3))^2/4; n = 1000; I0 = 1; deta0 = 0.01; L = 0.642; rho = 0.385; T = 162; solve = NDSolve[{D[u[t, x], t, t] - T*D[u[t, x], x, x]/rho == miu0*(miur)^2*S0*(n*I0)^2* exp (-(x - L/2)^2/0.001)*(cos (2*pi*329*t))^2/(rho*8*deta0^2), u[t, 0] == 0, u[t, L] == 0, u[0, x] == 0, Derivative[1, 0][u][0, x] == 0}, u[t, x], {t, 0, 20}, {x, 0, L}] 报错:: NDSolve::nlnum: The function value {0.,0.,0.,0.,0.,0.,0.,0.,0.,<<33>>,0. -2.58132*10^7 cos^2 exp pi^4,0. -3.7171*10^7 cos^2 exp pi^4,0. -5.05938*10^7 cos^2 exp pi^4,0. -6.60817*10^7 cos^2 exp pi^4,0. -8.36346*10^7 cos^2 exp pi^4,0. -1.03253*10^8 cos^2 exp pi^4,0. -1.24936*10^8 cos^2 exp pi^4,0.} is not a list of numbers with dimensions {50} at {t,u[t,x],(u^(1,0))[t,x]} = {0.202631,{0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.},{0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.}}. 画个图 {{u[t, x] -> InterpolatingFunction[{{0., 0.}, {0., 0.642}}, { 5, 5, 2, {1, 25}, {4, 6}, 0, 0, 0, 0, Automatic, {}, {}, False}, {{0.}, {0., 0.02675, 0.0535, 0.08025, 0.107, 0.13375, 0.1605, 0.18725, 0.214, 0.24075000000000002`, 0.2675, 0.29425, 0.321, 0.34775, 0.3745, 0.40125000000000005`, 0.428, 0.45475, 0.48150000000000004`, 0.50825, 0.535, 0.5617500000000001, 0.5885, 0.61525, 0.642}}, { Developer`PackedArrayForm, {0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100}, CompressedData[" 1:eJxTTMoPSmVkYGBIYcAFHJxxSo3Kj8qPIHkALbkO2g== "]}, {Automatic, Automatic}][t, x]}} Plot3D[Evaluate[u[x, t] /. First[%]], {x, 0, L}, {t, 0, 20}, PlotPoints -> 10] 结果什么也画不出来
今天想了一天，机车额定功率启动的图线方程是什么？应该是一个渐进函数，但是。。。望大神求解～
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