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

Current Status
Not Enrolled
Get Started

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

Recommended Courses

The fluctuations in the flow are caused by swirling flow structures, or eddies, that can exist in a wide range of sizes in the flow — some small, that are homogeneous and independent, and others large, governed by the flow field.  To study the effect of turbulence, the transport phenomena associated with all these vortices need to be resolved, which is not always possible due to computational hardware limitations. To mitigate this, the concept of time-averaging is introduced and a set of equations, called the Reynolds Averaging Navier-Stokes (RANS), are developed. In this SimCafe course, we will learn to model the turbulent flow inside a pipe using the Reynolds Averaged Navier-Stokes (RANS) approach.

In most industrial applications, forced convection is used for effective and efficient heat transfer in applications like steam turbines, heat exchangers, etc. When the forced fluid flow is turbulent, it increases the mixing rates and eventually leads to an increased heat transfer compared to a laminar fluid flow. These heat transfer rates can be calculated with the help of engineering simulations. In this SimCafe course, we consider a turbulent flow through a pipe with a heated section at the middle of the pipe.

A jet, which is a type of free shear flow, is exhaust from a confined source such as a nozzle into the quiescent surrounding. From an engineering standpoint, the jet centerline velocity, spreading rate, and penetration length are the parameters of interest. Based on the flow properties, jet flows can be laminar or turbulent. In this SimCafe course, we will learn to set up the models in Ansys Fluent and compare the laminar and turbulent jet flow results. We will also discuss the importance of the k-epsilon turbulence model in this course.