I want to plot the Van der Waals-equations, specifically the part in which the Van der Waals loop is shown. First I tried plotting it with the Plot3D[] function, tho the upper edges are very uneven and even with MaxRecursion set to 15 I couldn't get rid of the problem.

Plot3D[p, {V, 0, 0.001}, {T, 290, 320}, PlotTheme -> "Scientific", 
 PlotRange -> {0, 12000000}, AxesLabel -> {"V", "T", "p"}, 
 ImageSize -> 1100, Exclusions -> {V == 0, T == 0}, MaxRecursion -> 8,
  ViewPoint -> {0, -\[Infinity], 0}, ColorFunction -> Green]

When I used the ContourPlot3D[], I didn't had that problem.

ContourPlot3D[(R T)/(V - b) - a/V^2 == p, {V, 0, 0.001}, {T, 280, 
  340}, {p, 0, 12000000}, AxesLabel -> {"V", "T", "p"}, 
 ImageSize -> Large, AspectRatio -> 0.8]

Now I want to have a graph which a specific value for T (such graphs are called isotherms), which is plotted in the same ContourPlot3D. Also, I want to create a slider, in which I specify the value for T. I do know, that the Show[] function can be used, but don't know how to use it in this scenario since I want to plot two different things (a plane and graph) in one 3D plot.

Is there a way to to that? If yes, I'd be very thankful for your help :)

Thank you kglr! Tho does anyone understand why these uneven edges occur when using the Plot3D function and why there's a hole in the function plotted using ContourPlot3D?

uneven edges of a function plotted with Plot3D

Hole in plotted function using ContourPlot3D

  • $\begingroup$ the values for R,a and b? $\endgroup$ – kglr Oct 16 at 9:38
  • $\begingroup$ You can take a look at Show to combine the plots and at Manipulate for the slider. $\endgroup$ – Lukas Lang Oct 16 at 9:39
  • $\begingroup$ @kglr, R=8.31 :) $\endgroup$ – Rom38 Oct 16 at 9:39
  • $\begingroup$ Oh yes, sorry! R=8.314 a=363.7*10^(-3) b=42.7*108^(-6) $\endgroup$ – Henri Lila Oct 16 at 9:49
  • $\begingroup$ thank you Henri and @Rom38. $\endgroup$ – kglr Oct 16 at 10:01
  Show[ContourPlot3D[(R T)/(V - b) - a/V^2 == p, 
   {V, 0, 0.001}, {T,  280, 340}, {p, 0, 12000000}, 
    AxesLabel -> {"V", "T", "p"}, 
    ImageSize -> Large, AspectRatio -> 0.8, 
    MeshFunctions -> {#2 &, # &, #3 &}, 
    Mesh -> {{m}, 20, 20}, 
    MeshStyle -> {Directive[Thick, Red], Automatic, Automatic}], 
   Graphics3D[{Opacity[.5], Blue, 
    InfinitePlane[{{0, m, 0}, {1, m, 0}, {1, m, 1}}]}]], 
 {m, 280, 340}]

enter image description here


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