# The Viscous Channel Flow Applet (UT-JCFD)

THIS INTERACTIVE JAVA APPLET WAS DEVELOPED AT UT AUSTIN BY Lino Geo Lino Bailey, UNDER THE SUPERVISION OF PROFESSOR. Spyros A. Kinnas, 1999.

PERMISSION TO LINK TO THIS JAVA APPLET AND TO DOWNLOAD OR TO USE THE RELATED JAVA SOURCE CODE, MUST BE GRANTED BY PROFESSOR Spyros A. Kinnas ( kinnas@mail.utexas.edu ).

## Purpose:

Solves for the Navier-Stokes equations inside a 2-D channel using a finite-volume method (FVM). The related theory may be found in "NS-2D; Solver for Laminar Flows in 2-D" by J.K. Choi and S.A. Kinnas. The boundary conditions require:
• Uniform velocity at the inlet section.
• No-slip condition on the walls.
• Zero pressure at the outlet section.

## Important:

• The applet assumes laminar flow conditions.
• All units are listed.
• The length of the channel (L) is displayed in the lower-left area of the applet. The length is a fractional width of the applet's window and only changes if you are viewing the applet in a JVM (a Java Virtual Machine such as Netscape) that allows you to resize the applet's window (most 'web browser' JVM's, such as Netscape, do not allow window resizing). Changing the length, however, should not be necessary since the inlet and outlet values can be changed to achieve the desired proportions.
• The Reynolds number (Re) is displayed in the lower-left area of the applet. It is calculated from the input data as follows: Re = U * h1 / visc. In order for the code to converge, Re must be much less than 1000; therefore, the code used by this applet has declared that Remax = 500 and the input variables (U, h1, or visc) will be adjusted to ensure that Re <= Remax.
• The velocity is non-dimensionalized by the in flow (Uin).
• The pressure is non-dimensionalized by rho Uin^2.

## Interaction:

(note that the variables are self-limiting - the variables are automatically adjusted to stay within valid boundaries):
• You can change the shape of the channel by dragging any of the 3 red sizing handles (you can also use the Shift, Control, or Option (Win: right-mouse) keys while dragging to constrain movements).
• You can move the entire channel around in the window by dragging it (you can also use the Shift key while dragging to restore the channel's default position).
• You can show or hide the boundary of the channel by clicking the "Show Channel" button (slower to redraw if shown).
• You can show or hide the facing side of the channel by clicking the "Show Side" button (slower to redraw if shown).
• You can show or hide the nodes of the channel by clicking the "Show Nodes" button (slower to redraw if shown).
• You can show or hide the cell outlines of the channel by clicking the "Show Cells" button (slower to redraw if shown).
• You can change the input height of the channel by entering a value in the "h1" text field or by dragging its sizing handle.
• You can change the output height of the channel by entering a value in the "h2" text field or by dragging its sizing handle.
• You can change the vertical offset height of the channel by entering a value in the "d" text field or by dragging its sizing handle.
• You can change the maximum number of iterations (needed for the solution to converge) used in determining the solution by entering a value in the "iter" text field. NOTE: YOU MUST CHANGE THE NUMBER OF ITERATIONS AND CHECK THE EFFECT ON THE RESULTS.
• You can change the flow rate by entering a value in the "U" text field.
• You can change the viscosity by entering a value in the "visc" text field (WATCH UNITS).
• You can change the number of m-subdivisions (horizontal) by entering a value in the "m" text field.
• You can change the number of n-subdivisions (vertical) by entering a value in the "n" text field. NOTE: YOU MUST CHANGE m,n and CHECK THE EFFECT ON THE RESULTS.

## Calculating Results:

• Adjust the input variables as desired (see variables above).
• Calculate the fluid conditions inside the laminar channel by clicking the math symbols icon ( ) in the upper-right of the applet. If you need to interrupt a calculation loop, then click the math symbols icon again.
• Once the applet has started it will begin the calculations by looping from 0 to "iter" and then open a new results window.
• The results window has buttons to turn on and off respective results. There is also a 'print' button which opens a window for selecting which variables to print out to your JVM's "Java Console Window." The printed results can then be copied or examined from the Java Console Window. Multiple result windows can be left open for visual comparison.

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