level 2
hsfakj
楼主
mma可以实现微分方程组的分段计算么
sol1 = NDSolve[{rQr'[r] ==
Piecewise[{{i^2/(1.4*10^5*E^(0.0035*t[r]))*r, r < 0.004}, {0,
0.004 <= r < 0.015}}],
t'[r] ==
Piecewise[{{-Qr/k, r < 0.004}, {-Qr/0.2, 0.004 <= r < 0.015}}],
rQr[0] == 0, t[0.002] == 390.15}, rQr, {r, 0, 0.015},
MaxSteps -> Infinity]
Plot[Evaluate[rQr[r]/r /. sol1], {r, 0, 0.015},
PlotRange -> {0, 3000},
AxesLabel -> {"金属线半径m", "热通量W/\!\(\*SuperscriptBox[\(m\), \(2\)]\)"},
PlotLabel -> "金属线内热通量分布"]
2021年03月22日 01点03分
1
sol1 = NDSolve[{rQr'[r] ==
Piecewise[{{i^2/(1.4*10^5*E^(0.0035*t[r]))*r, r < 0.004}, {0,
0.004 <= r < 0.015}}],
t'[r] ==
Piecewise[{{-Qr/k, r < 0.004}, {-Qr/0.2, 0.004 <= r < 0.015}}],
rQr[0] == 0, t[0.002] == 390.15}, rQr, {r, 0, 0.015},
MaxSteps -> Infinity]
Plot[Evaluate[rQr[r]/r /. sol1], {r, 0, 0.015},
PlotRange -> {0, 3000},
AxesLabel -> {"金属线半径m", "热通量W/\!\(\*SuperscriptBox[\(m\), \(2\)]\)"},
PlotLabel -> "金属线内热通量分布"]