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Consider a figure looking like the annular cylinder, with the longitudinal size extended from $z = 1$ to $z = 10$, but with the transverse boundaries depending on the distance from the origin $z$: the inner radius is $R_{\text{inn}}(z) = z\cdot \tan(\theta_{1})$, while the outer one is $R_{\text{out}} = z \cdot \tan(\theta_{2})$, with $\theta_{1}=0.0134$ rad and $\theta_{2} = 0.269$ rad. Please find attached the figure:

enter image description here

Could you please tell me how to specify this figure in Mathematica? It has only the standard Annulus figure, which is a 2D transverse projection only.

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  • $\begingroup$ What is "longitudinal size" ? $\endgroup$
    – Ulrich Neumann
    Jan 23 at 13:18
  • $\begingroup$ @UlrichNeumann : the length along the z axis. $\endgroup$
    – John Taylor
    Jan 23 at 13:24
  • $\begingroup$ Try ParametricPlot3d $\endgroup$
    – Ulrich Neumann
    Jan 23 at 13:24

3 Answers 3

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Here's a couple CSG approaches:

zθConicalFrustum[z1_, z2_, θ_] := 
  ConvexHullMesh[Join @@ (Map[Append[#], CirclePoints[# Tan[θ], 100]] & /@ {z1, z2})]

fuot = zθConicalFrustum[1, 10, 0.269];
fin = zθConicalFrustum[1, 10, 0.0134];

BoundaryMeshRegion[RegionDifference[fuot, fin], 
  PlotTheme -> "Minimal", BaseStyle -> Opacity[0.6]]


zθCone[z_, θ_] := BoundaryDiscretizeRegion[Cone[{{0, 0, z}, {0, 0, 0}}, z Tan[θ]]]

reg = RegionDifference[
  RegionDifference[zθCone[10, 0.269], zθCone[10, 0.0134]], 
  zθCone[1, 0.269]
];

BoundaryMeshRegion[reg, PlotTheme -> "Minimal", BaseStyle -> Opacity[0.6]]

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Method-1

  • At first we draw the sectional graphics;
θ1 = .0134;
θ2 = .269;
Plot[{z*Tan[θ1], z*Tan[θ2]}, {z, 1, 10}, 
 Filling -> {1 -> {2}}, AxesOrigin -> {0, 0}, 
 AspectRatio -> Automatic]

enter image description here

  • Then we revolution the four boundary lines of the sectional graphics.
SetOptions[RevolutionPlot3D, RevolutionAxis -> "X", Mesh -> None, 
  Boxed -> False, Axes -> False];
Show[RevolutionPlot3D[{{z, z*Tan[θ1]}, {z, 
    z*Tan[θ2]}}, {z, 1, 10}, 
  PlotStyle -> {Directive[Opacity[.2], Blue], 
    Directive[Opacity[.2], Blue]}], 
 RevolutionPlot3D[{{1, r}}, {r, z*Tan[θ1] /. z -> 1, 
   z*Tan[θ2] /. z -> 1}, PlotStyle -> Cyan], 
 RevolutionPlot3D[{{10, r}}, {r, z*Tan[θ1] /. z -> 10, 
   z*Tan[θ2] /. z -> 10}, PlotStyle -> Red], PlotRange -> All, 
 BoxRatios -> Automatic]

enter image description here

Method-2

  • To calculate its volume we use ParametricRegion.
reg = ParametricRegion[{z, r*Cos[t], 
    r*Sin[t]}, {{z, 1, 10}, {r, z*Tan[θ1], 
     z*Tan[θ2]}, {t, 0, 2 π}}];
reg // Volume
(* RegionPlot3D[reg, PlotStyle -> Opacity[.2], PlotPoints -> 80] *)

79.3201

Method-3

Since CSGRegion seems not work for this cases, we try to use OpenCascadeLink.

Needs["OpenCascadeLink`"];
θ1 = .0134;
θ2 = .269;
shape1 = 
  OpenCascadeShape[Cone[{{10, 0, 0}, {0, 0, 0}}, 10*Tan[θ2]]];
shape2 = 
  OpenCascadeShape[Cone[{{10, 0, 0}, {0, 0, 0}}, 10*Tan[θ1]]];
shape3 = OpenCascadeShape[Cuboid[{0, -1, -1}, {1, 1, 1}]];
shape = OpenCascadeShapeDifference[
   OpenCascadeShapeDifference[shape1, shape2], shape3];
bmesh = OpenCascadeShapeSurfaceMeshToBoundaryMesh[shape, 
   "ShapeSurfaceMeshOptions" -> {"AngularDeflection" -> 0.1}];
bm = BoundaryMeshRegion[bmesh];
bm // Volume
RegionPlot3D[bm, PlotStyle -> Opacity[.2], Boxed -> False, 
 ColorFunction -> Hue]

79.1933

enter image description here

Needs["OpenCascadeLink`"];
Needs["NDSolve`FEM`"];
θ1 = .0134;
θ2 = .269;
pts = {{1, 1*Tan[θ1]}, {10, 10*Tan[θ1]}, {10, 
    10*Tan[θ2]}, {1, 1*Tan[θ2]}};
poly = Polygon[PadRight[#, 3] & /@ pts];
shape = OpenCascadeShape[poly];
axis = {{0, 0, 0}, {1, 0, 0}};
sweep = OpenCascadeShapeRotationalSweep[shape, axis, 2 π];
bmesh = OpenCascadeShapeSurfaceMeshToBoundaryMesh[sweep, 
   "ShapeSurfaceMeshOptions" -> {"AngularDeflection" -> 0.1}];
RegionPlot3D[BoundaryMeshRegion[bmesh], PlotStyle -> Opacity[.2], 
 Boxed -> False]

enter image description here

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  • 2
    $\begingroup$ (+1) you could also use the OpenCascadeRotationalSweep to do the speed in OC. $\endgroup$
    – user21
    Jan 24 at 14:12
  • 1
    $\begingroup$ @user21 Thanks! updated. $\endgroup$
    – cvgmt
    Jan 24 at 14:57
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That seems a rather skinny cylinder:

p1 = Tan[0.0134] ;
p2 = Tan[0.269];
ParametricPlot3D[{p1 z Sin[phi], p2 z Cos[phi], z}, {z, 1, 10}, {phi, 0, 2 Pi}]

enter image description here

With a little more breath:

p1 = Tan[0.0134] 5;
ParametricPlot3D[{p1 z Sin[phi], p2 z Cos[phi], z}, {z, 1, 10}, {phi, 
  0, 2 Pi}]

enter image description here

Addendum

The same using regions:

p1 = Tan[0.0134] 5;
p2 = Tan[0.269];
ImplicitRegion[{x^2/(p1 z)^2 + y^2/(p2 z )^2 == 1 && 1 <= z <= 10}, {x, y, z}] // Region

enter image description here

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  • $\begingroup$ Thank you very much! Do you also know how to convert the plot into a region, for being able to use the commands such as RegionIntersection for this region? $\endgroup$
    – John Taylor
    Jan 23 at 13:39
  • 1
    $\begingroup$ I added another possibility using regions. $\endgroup$
    – Daniel Huber
    Jan 23 at 14:05
  • $\begingroup$ Excuse me, I just noticed that the figure differs from the desired one (in transverse dimensions). This is because of improper description in the question. I have modified the question. $\endgroup$
    – John Taylor
    Jan 23 at 15:46
  • $\begingroup$ Simply exchange z and x. $\endgroup$
    – Daniel Huber
    Jan 23 at 15:56

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