Computing Volumes

images/download/attachments/113546447/Vol_Ini.jpg

Introduction

In the software you can compute volumes in different situations:

  • Volume of a closed surface.

  • Volume over or under a certain level of liquid.

  • Volume between two superimposed surfaces (not illustrated here).

Exercise overview

In this exercise, we will see how to:

  • Calculate directly the volume of a closed surface

  • Compute the volume at a certain level of liquid

  • Evaluate the maximum level of a mountain lake

  • Calculate intersections between surfaces

  • Make a “constraint meshing”

The files used in this tutorial are FuelTank.3dr and MountainLake.3dr

Calculating the volume of a tank

Displaying the properties

Open the file FuelTank.3dr.

The surface of this tank is completely closed

  • Select the object

  • Right click to open the contextual menu

  • Open the command Properties

  • You should see a volume of 4m3

When a surface contains no hole or free contour, the volume is automatically calculated in the property sheet

Computing the level at a certain height of liquid

Select the object and launch the command Volume from Elevation. Set the Direction: X=0; Y=0; Z=1. Enter a level of liquid of 0.5 in List of distances and click Preview.

images/download/attachments/113546447/image2019-9-23_12-57-5.png Figure 1: Get the volume over and under a liquid level

The software creates a label in order to display the two volumes, above and below the plane.

Calculating the volume of a lake

Open the file MountainLake.3dr.

Determining the maximum water height

The model represents a mountain landscape and the goal is to evaluate the maximum capacity of a mountain lake.

  • Select the object

  • Launch the command Volume from Elevation

  • Set the Direction: X=0; Y=0; Z=1.

  • Adjust the water height to find the maximum water height. For this, you must zoom to verify that there is no junction here between the inside and the outside of the lake

  • You should find 2339.6 m

  • Press Preview then OK to validate the results

images/download/attachments/113546447/image2019-9-23_13-1-46.png Figure 2: Adjusting the water level to find the maximum capacity of the mountain lake

The result of the volume calculation, here, is not meaningful because it represents the sum of the volumes inside AND outside the lake. Here we need only the volume inside.

Computing the contour of the lake

  • Select both the mountain surface and created plane

  • Launch the command Intersection

  • You should see that the intersection contours are calculated

  • Click OK Exit to keep the result

  • Select the water level and hide it

images/download/attachments/113546447/Im4Fr.PNG Figure 3: Using the command Intersection to get the contour of the lake

Separating the lake surface from the rest of the mountain

  • Select both the mountain surface and the contours

  • Launch the command Constraint Mesh

  • Check only Cut in parts

  • Click Preview to calculate the result, and then OK to validate

The mesh has been cut along the contours.

Calculating the volume of the lake

  • Click on the lake and right click to Show only this object

  • Launch the command Volume from Elevation

  • Adjust the water height to be at the maximum water height. You can click on the arrow button at the end of list of distance, select option Nearest 3D Projection and select point on the top border of the lake.

  • Click OK

  • You should obtain a volume of 5.7 million of m3

images/download/attachments/113546447/Im6Fr.PNG Figure 4: Computing the volume of the lake: 5.7 million of m3

Calculating the volume at several levels

It is also possible to compute a liquid volume all over the mesh according to regular levels. The resulting volumes can be displayed through labels and customizable reports or can be exported in CSV format.

  • Click on the lake and right click to Show only this object

  • Launch the command Volume from Elevation

  • Put the options as below:

    • Direction: X=0; Y=0; Z=1.

    • Choose Regular steps: 1m From 2310 To 2339.6 thanks to Custom mode.

  • Click OK

The intersection lines between each plane and the mesh can also be extracted via the command Intersection.