Versions Compared


  • This line was added.
  • This line was removed.
  • Formatting was changed.

<div style="background-color: yellow; border: 2px solid red; margin: 4px; padding: 2px; font-weight: bold; text-align: center;">
This page has been moved to <a href=""></a>
Click in the link above if you are not automatically redirected in 10 seconds.
<meta http-equiv="refresh" content="10; URL=''" />

Include Page
FLUENT Google Analytics
FLUENT Google Analytics
Include Page
Unsteady Flow Past a Cylinder - Panel
Unsteady Flow Past a Cylinder - Panel

Unsteady Flow Past a Cylinder

Created using ANSYS 13.0

Problem Specification

Image Added

Consider the unsteady state case of a fluid flowing past a cylinder, as illustrated above. For this tutorial we will use a Reynolds Number of 120. In order to simplify the computation, the diameter of the cylinder is set to 1 m, the x component of the velocity is set to 1 m/s and the density of the fluid is set to 1 kg/m^3. Thus, the dynamic viscosity must be set to 8.333x10^-3 kg/m*s in order to obtain the desired Reynolds number.

Compared to the steady case, the unsteady case includes an additional time-derivative term in the Navier-Stokes equations:


\frac{\partial \vec{u}}{\partial t} + \rho (\vec{u}\cdot \triangledown)\vec{u} = -\triangledown p + \mu \triangledown^{2} \vec{u}

The methods implemented by FLUENT to solve a time dependent system are very similar to those used in a steady-state case.  In this case, the domain and boundary conditions will be the same as the Steady Flow Past a Cylinder.  However, because this is a transient system, initial conditions at t=0 are required.  To solve the system, we need to input the desired time range and time step into FLUENT.  The program will then compute a solution for the first time step, iterating until convergence or a limit of iterations is reached, then will proceed to the next time step, "marching" through time until the end time is reached.

Go to Step 1: Pre-Analysis & Start-Up

Go to all FLUENT Learning Modules


Author: John Singleton and Rajesh Bhaskaran