Thursday, June 20, 2024

How to calculate OSI, Ig factor, Area averaged wall shear and time averaged wall shear in Ansys fluent?

Calculating the Oscillatory Shear Index (OSI), Ig factor, Area Averaged Wall Shear Stress (AAWSS), and Time Averaged Wall Shear Stress (TAWSS) in ANSYS Fluent involves several steps. Here's a general guide to help you with the process:

ERROR: The UDF library you are trying to load (libudf) is not compiled for parallel use on the current platform (win64)

This error indicates that you're trying to load a User Defined Function (UDF) library in ANSYS Fluent that wasn't compiled for parallel processing on your 64-bit Windows system (win64).


How can I prevent ANSYS Mechanical from renumbering cell zones/walls after mesh refinement, thereby ensuring my journal file remains compatible?

 ANSYS Mechanical renumbering cell zones/walls after mesh refinement is a common issue when dealing with journal files. Here are two approaches to address this:

Wednesday, June 19, 2024

How to define opening boundary condition in Ansys Fluent ?

 In ANSYS Fluent, an opening boundary condition, also referred to as a pressure outlet boundary condition, is used to simulate an outlet where the flow exits the computational domain. It allows the fluid to leave the domain freely without any restrictions. Here's how to define it:

Sunday, June 16, 2024

How to plot bed expansion in Ansys Fluent ?

 I have simulated unsteady fluidized bed at different superficial velocities and got result. now i want to plot a graph of expansion of bed vs superficial velocity. does fluent contain any option (xy plot) ?

Fluent itself doesn't have a dedicated function to directly plot bed expansion vs. superficial velocity. However, you can achieve this by utilizing built-in features and potentially a User Defined Function (UDF) depending on your approach. Here are two methods you can consider:


Colour variable'Velocity Meridional' does not exist - in ansys cfx how to fix it ?

 The error message "Colour variable 'Velocity Meridional' does not exist" in ANSYS CFX indicates that the report template you're using is trying to reference a variable that doesn't exist in your simulation data. Here are a few ways to fix this issue:

  1. Verify Variable Name:
  • Double-check the spelling of "Velocity Meridional" in the report template. Ensure it matches the exact name of the variable in your simulation data.
  • In CFX, meridional velocity typically refers to the velocity component in the circumferential direction. Look for variables named "Circumferential Velocity" or "Theta Velocity" in the list of available solution variables.

The Influence of Prandtl Number on Shear Stress and Heat Transfer in Compressible Boundary Layers

 You're right, in compressible boundary layers, increasing the Prandtl number (Pr) generally leads to a decrease in shear stress (skin friction) and Stanton number. Here's why:

Prandtl Number (Pr):

Pr is the ratio of momentum diffusivity (ν) to thermal diffusivity (α). It represents the relative ease with which momentum and heat diffuse within a fluid.

  • Low Pr: When Pr is low (typical for gases), momentum diffuses more readily than heat. This means velocity gradients (shear) are higher near the wall, resulting in higher skin friction.
  • High Pr: As Pr increases (typical for liquids), thermal diffusivity becomes more dominant. Heat diffuses faster, reducing the temperature gradients near the wall. This, in turn, affects the viscosity (which is temperature-dependent) and reduces the shear stress at the wall.

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