28.7 Quadric Surfaces

If you want to display data on a line (2D), plane (3D), circle (2D), sphere (3D), or general quadric surface, you can specify the surface by entering the coefficients of the quadric function that defines it. This feature provides you with an explicit method for defining surfaces. See Sections  28.5 and 28.6 for additional methods for creating line and plane surfaces.

To create a quadric surface, you will use the Quadric Surface dialog box (Figure  28.7.1).

Surface $\rightarrow$ Quadric...

Figure 28.7.1: The Quadric Surface Dialog Box

The steps for creating the quadric surface are as follows:

1.   Decide which type of quadric surface you want to create. In 3D, choose Plane, Sphere, or (general) Quadric in the Type drop-down list. In 2D, choose Line, Circle, or Quadric.

2.   Specify the defining equation for the surface in SI units.

• Line or plane surface: If you have selected Line (in 2D) or Plane (in 3D) as the surface type, the surface will consist of all points on the domain that satisfy the equation $ix*x + iy*y + iz*z = \mbox{distance}$. You will input ix (the coefficient of $x$), iy (the coefficient of $y$), iz (the coefficient of $z$), and distance (the distance of the line or plane from the origin) in the fields to the right of the Type drop-down list. When you click on the Update button under the Quadric Function heading, the display of the quadric function coefficients will change to reflect your inputs.

• Circle or sphere surface: If you have selected Circle (in 2D) or Sphere (in 3D) as the surface type, the surface will consist of all points on the domain that satisfy the equation $(x-x0)^2 + (y-y0)^2 + (z-z0)^2= r^2$. You will input x0,y0,z0 (the $x$, $y$, and $z$ coordinates of the sphere or circle's center) and r (the radius) in the fields to the right of the Type drop-down list. When you click on the Update button under the Quadric Function heading, the display of the quadric function coefficients will change to reflect your inputs.

• Quadric surface: If you have selected Quadric as the surface type, the surface will consist of all points in the domain that satisfy the general quadric function $Q= \mbox{value}$. You will input the coefficients of the quadric function $Q$ (the coefficients of the terms x $^2$, y $^2$, z $^2$, xy, yz, zx, x, y, z and the constant term) directly in the Quadric Function box, and you will set value to the right of the Type drop-down list. Note that the Update button will be disabled when you choose this type of surface.

3.   If you do not want to use the default name assigned to the surface, enter a new name under New Surface Name. The default name is the concatenation of the surface type and an integer which is the new surface ID (e.g., sphere-slice-7 or quadric-slice-10). (If the New Surface Name you enter is the same as the name of a surface that already exists, ANSYS FLUENT will automatically assign the default name to the new surface when it is created.)

The surface name that you enter must begin with an alphabetical letter. If your surface name begins with any other character or number, ANSYS FLUENT will not accept the entry.

4.   Click on the Create button to create the new surface.

If you want to check that your new surface has been added to the list of all defined surfaces, or you want to delete or otherwise manipulate any surfaces, click on the Manage... button to open the Surfaces dialog box. See Section  28.11 for details.