MatLab PDE绘图问题

Question

我是Matlab环境的新手，我正在Matlab（2014b）上进行热传递模拟。我打算有不同材料的多层墙（现在，只有一种材料 - 铜），并将结果显示在一张图上。一切工作正常，直到我试图将第三层墙追加到情节。 下面是基本变量和几何形状对于PDE解算器（R3-R0）的定义：

k = 400; 
rho = 8960; 
specificHeat = 386; 
thick = .01; 
stefanBoltz = 5.670373e-8; 
hCoeff = 1; 
ta = 300; 
emiss = .5; 

c = thick*k; 
a = sprintf('2*%g + 2*%g*%g*u.^3', hCoeff, emiss, stefanBoltz); 
f = 2*hCoeff*ta + 2*emiss*stefanBoltz*ta^4; 
d = thick*rho*specificHeat; 

r0 = [3 4 0 1 1 0 1 1 1.3 1.3]; 
r1 = [3 4 0 1 1 0 0.6 0.6 1 1]; 
r2 = [3 4 0 1 1 0 0.3 0.3 0.6 0.6]; 
r3 = [3 4 0 1 1 0 0 0 0.3 0.3]; 

现在，下面的代码段，计算通过所述壁的底部层（R3）的热传递，与输入1000 [K]的温度：

gdm = r3'; 
g = decsg(gdm, 'R3', ('R3')'); 
hmax = .1; % element size 
[p, e, t] = initmesh(g, 'Hmax', hmax);  

numberOfPDE = 1; 
pb = pde(numberOfPDE); 
pg = pdeGeometryFromEdges(g); 
uBottom = pdeBoundaryConditions(pg.Edges(1),'u',1000); 
pb.BoundaryConditions = uBottom; 

u = pdenonlin(pb,p,e,t,c,a,f, 'jacobian', 'lumped'); 
fprintf('Temperature at the top edge of the plate = %5.1f degrees-K\n', ... 
u(4)); 

figure 
pdeplot(p, e, t, 'xydata', u, 'contour', 'on', 'colormap', 'jet') 

hold on 

“持有”，我基本上重复前面的代码为“R2”矩形，为“u（4）”（先前层的输出）的输入温度后，随后是最后一位代码：

hold off 
axis([0,1,0,2]) 
caxis manual 
caxis([u(4) 1000]); 
colorbar; 

正如我所说，这是所有工作，第一层和第二层的结果是在同一个阴谋。但是当我重复第三层（r1）的过程并且将结果绘制到原始图中（当然，“hold off”位在代码的最后），该图仅显示结果第三层。我不确定这是否是Matlab的一些限制，或者如果我的解决方案是错误的，所以我想问一些帮助或方向。在此先感谢

下面是更好地了解全码：

k = 400; 
rho = 8960; 
specificHeat = 386; 
thick = .01; 
stefanBoltz = 5.670373e-8; 
hCoeff = 1; 
ta = 300; 
emiss = .5; 

c = thick*k; 
a = sprintf('2*%g + 2*%g*%g*u.^3', hCoeff, emiss, stefanBoltz); 
f = 2*hCoeff*ta + 2*emiss*stefanBoltz*ta^4; 
d = thick*rho*specificHeat; 

r0 = [3 4 0 1 1 0 1 1 1.3 1.3]; 
r1 = [3 4 0 1 1 0 0.6 0.6 1 1]; 
r2 = [3 4 0 1 1 0 0.3 0.3 0.6 0.6]; 
r3 = [3 4 0 1 1 0 0 0 0.3 0.3]; 
%--------------------------------------------------------- 

gdm = r3'; 
g = decsg(gdm, 'R3', ('R3')'); 
hmax = .1; % element size 
[p, e, t] = initmesh(g, 'Hmax', hmax); 

numberOfPDE = 1; 
pb = pde(numberOfPDE); 
pg = pdeGeometryFromEdges(g); 
uBottom = pdeBoundaryConditions(pg.Edges(1),'u',1000); 
pb.BoundaryConditions = uBottom; 

u = pdenonlin(pb,p,e,t,c,a,f, 'jacobian', 'lumped'); 
fprintf('Temperature at the top edge of the plate = %5.1f degrees-K\n', ... 
u(4)); 

figure 
pdeplot(p, e, t, 'xydata', u, 'contour', 'on', 'colormap', 'jet') 

hold on 

%---------------------------------------------------------------------- 
gdm = r2'; 
g = decsg(gdm, 'R2', ('R2')'); 
hmax = .1; % element size 
[p, e, t] = initmesh(g, 'Hmax', hmax); 

numberOfPDE = 1; 
pb = pde(numberOfPDE); 
pg = pdeGeometryFromEdges(g); 
uBottom = pdeBoundaryConditions(pg.Edges(1),'u',u(4)); 
pb.BoundaryConditions = uBottom; 

u = pdenonlin(pb,p,e,t,c,a,f, 'jacobian', 'lumped'); 
fprintf('Temperature at the top edge of the plate = %5.1f degrees-K\n', ... 
u(4)); 

pdeplot(p, e, t, 'xydata', u, 'contour', 'on', 'colormap', 'jet') 

%---------------------------------------------------------------------------- 
gdm = r1'; 
g = decsg(gdm, 'R1', ('R1')'); 
hmax = .1; % element size 
[p, e, t] = initmesh(g, 'Hmax', hmax); 

numberOfPDE = 1; 
pb = pde(numberOfPDE); 
pg = pdeGeometryFromEdges(g); 
uBottom = pdeBoundaryConditions(pg.Edges(1),'u',u(4)); 
pb.BoundaryConditions = uBottom; 

u = pdenonlin(pb,p,e,t,c,a,f, 'jacobian', 'lumped'); 
fprintf('Temperature at the top edge of the plate = %5.1f degrees-K\n', ... 
u(4)); 

pdeplot(p, e, t, 'xydata', u, 'contour', 'on', 'colormap', 'jet') 

%---------------------------------------------------------------------------- 
gdm = r0'; 
g = decsg(gdm, 'R0', ('R0')'); 
hmax = .1; % element size 
[p, e, t] = initmesh(g, 'Hmax', hmax); 

numberOfPDE = 1; 
pb = pde(numberOfPDE); 
pg = pdeGeometryFromEdges(g); 
uBottom = pdeBoundaryConditions(pg.Edges(1),'u',u(4)); 
pb.BoundaryConditions = uBottom; 

u = pdenonlin(pb,p,e,t,c,a,f, 'jacobian', 'lumped'); 
fprintf('Temperature at the top edge of the plate = %5.1f degrees-K\n', ... 
u(4)); 

pdeplot(p, e, t, 'xydata', u, 'contour', 'on', 'colormap', 'jet') 

%hold off 

axis([0,1,0,2]) 
%caxis manual 
caxis([u(4) 1000]); 

Answer 1

出于某种原因（这不完全清楚，我）的pdeplot函数内部调用hold off。

因此，要获得理想的结果，您需要在每次致电pdeplot后添加一个hold on。