(a) Disable the Global Range option.
(b) Select Velocity... and X Velocity from the Contours of drop-down lists.
(c) Select x=130, x=165, and x=95 from the Surfaces selection list, and deselect y=0.
(d) Click Display and close the Contours panel.
The velocity profile becomes more uniform as the fluid passes through the porous media. The velocity is very high at the center (the area in red) just before the nitrogen enters the substrate and then decreases as it passes through and exits the substrate. The area in green, which corresponds to a moderate velocity, increases in extent.
Figure : Contours of the X Velocity on the x=95, x=130, and x=165 Surfaces
11. Use numerical reports to determine the average, minimum, and maximum of the velocity distribution before and after the porous substrate. Report /Surface Integrals...
(a) Select Mass-Weighted Average from the Report Type drop-down list.
(b) Select Velocity and X Velocity from the Field Variable drop-down lists. (c) Select x=165 and x=95 from the Surfaces selection list. (d) Click Compute. (e) Select Facet Minimum from the Report Type drop-down list and click Compute again. (f) Select Facet Maximum from the Report Type drop-down list and click Compute again. (g) Close the Surface Integrals panel.
The numerical report of average, maximum and minimum velocity can be seen in the main FLUENT console, as shown in the following example:
The spread between the average, maximum, and minimum values for X velocity gives the degree to which the velocity distribution is non-uniform. You can also use these numbers to calculate the velocity ratio ., the maximum velocity divided by the mean velocity) and the space velocity ., the product of the mean velocity and the substrate length).
Custom field functions and UDFs can be also used to calculate more complex measures of non-uniformity, such as the standard deviation and the gamma uniformity index.
Summary
In this tutorial, you learned how to set up and solve a problem involving gas flow through porous media in FLUENT. You also learned how to perform appropriate
post-processing to investigate the flow field, determine the pressure drop across the porous media and non-uniformity of the velocity distribution as the fluid goes through the porous media.
Further Improvements
This tutorial guides you through the steps to reach an initial solution. You may be able to obtain a more accurate solution by using an appropriate higher-order discretization scheme and by adapting the grid. Grid adaption can also ensure that the solution is independent of the grid. These steps are demonstrated in Tutorial 1.
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