Flow Past a Cylinder – Estimation of Lift Force using User Defined Functions

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Most fluid flows are relatively simple, like the air flow over a car or water flow inside a pipe. A good understanding of flow physics helps engineers design efficient products. The flow characteristics for such problems can be studied using CFD models without the need for any additional customization. Ansys Fluent provides many in-built models to study such regular flow phenomena. However, other applications sometimes require additional customization, which in Ansys Fluent can be provided using the User Defined Functions or UDFs. A user-defined function, or UDF, is a C or C++ code that can be dynamically loaded into Ansys Fluent to enhance its standard features. For example, engineers may use a UDF to customize boundary conditions, material property definitions, and surface and volume reaction rates. This course will demonstrate the use of UDFs for integrating the lift coefficient on a canonical problem — the flow past a cylinder.

This SimCafe course was developed by Dr. Rajesh Bhaskaran, Swanson Director of Engineering Simulation at Cornell University, and Lara Camille Backer in partnership with Ansys. It serves as an e-learning resource to integrate industry-standard simulation tools into courses and provides a resource for supplementary learning outside the classroom. In this course, we will discuss the importance of UDFs on solving for the lift force over a cylindrical surface by following the end-to-end workflow in Ansys Workbench.

For more ways to learn, check out the Cornell edX course, A Hands-on Introduction to Engineering Simulations at ansys.com/cornell.

Cornell University also offers a Fluid Dynamics Simulations Using Ansys online certificate authored by Dr. Rajesh Bhaskaran. Learn more here: https://ecornell.cornell.edu/fluiddynamics

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