Water Flow Tutorial Overview

This page contains an in-depth visualization tutorial for a water flow simulation.

Description of Simulation Data

This tutorial uses the dbreak3d dataset -- available at: http://www.visitusers.org/index.php?title=Tutorial_Data

The dataset simulates the evolution of water and air in a water tank after an interface holding a column of water is instantaneously removed. The data was generated using the OpenFOAM open source CDF simulator, using a two-phase volume of fluid (VOF) method to resolve the interface between the water and air.

Our case is a 3D variant of the 2D Dam Break OpenFOAM tutorial, which is described in detail at: http://www.openfoam.org/docs/user/damBreak.php. Several changes to the 2D tutorial input deck were necessary to create the 3D simulation. We started with guidance from http://www.calumdouglas.ch/openfoam-example-3d-dambreak/. Our OpenFOAM input deck is available at: https://github.com/cyrush/dbreak3d_vtutorial. We ran the simulation on a single node of the insight cluster at Clemson (Special thanks to Vetria Byrd and Galen Collier of Clemson for access to this resource)

After running the simulation we converted the OpenFOAM output to Silo data files. The Silo files are compressed and contain the subset of the variables of interest for this tutorial. The final dataset has 160 silo files holding 4 seconds of the simulation at time intervals of 0.025 seconds [40 timesteps per second].

You can open the entire time series in VisIt using the dbreak3d_fluid.visit file.

Variables

The simulation is run in an Eulerian fashion: The mesh itself is static -- but the variables evolve to reflect the physics.

Each of the 160 time steps contains three variables:

  • U {u,v,w} -- Velocity vector
  • alpha1 -- Volume fraction of water (0.0 - 1.0)
  • p_rgh -- A pressure term

Boundaries

In addition to the fluid data the dbreak3d_boundaries.silo data file contains the boundaries of the water tank. We will use this additional file to bring context to our visualizations.

Exploring the Fluid Data

Exploring the Velocity Vector Field

Rendering a Movie of the Fluid Data