TCELL_FLOW
Flow Solutions in a T-Cell

TCELL_FLOW is a dataset directory which contains velocity solutions to a time-dependent incompressible parameterized flow problem in a 2D T-cell.

The "T-Cell" region is a T-shaped region contained in a subset of the unit square [01]x[01]. The top half of the region is a channel open to the left and right, with a rectangular recess in the bottom. The left channel opening extends from [0.0,0.5] to [0.0,1.0], and the right channel from [1.0,0.5] to [1.0,1.0]. The recess is a square, whose bottom extends from [0.25,0.0] to [0.75,0.0], and which extends upward to meet the channel.

             +--------------------+
             +--------------------+
            ->                      ->
      Inlet --->      Channel       --->  Outlet
            ->                      ->
             +-----+          +---+
             +----+|  Recess  |+--+
                  ||          || 
             Void ||          || Void
                  |+----------+|
                  +------------+
      

(Some runs of this problem were made earlier, with a cruder 41 by 41 uniformly spaced grid of nodes, which were arranged into 600 6-node elements).

The time-dependent incompressible 2D Navier-Stokes equations are to be applied in the region. No-slip and no-penetration conditions are applied along the walls. The inlet on the left of the region is open, and here a parabolic inflow is specified, whose strength is controlled by a parameter alpha. The outlet on the right is open, where the velocity is required to have zero vertical component, and zero horizontal derivative. The dynamic viscosity is taken to be nu=1/300.

The steady state solution is computed for the particular value alpha=1/3. Using the steady state solution as initial condition, the time-dependent problem is solved over the interval 0<=t<=0.1, with alpha = 5/3 for timesteps 1 through 250, and then alpha = 1/3 for timesteps 251 through 500. The two instantaneous changes to alpha induce violent transient behaviors.

The goal is to extract typical modes of behavior of the solution. Such a set of modes may then be used as a finite element basis that is highly tuned to the physics of the problem, so that a very small set of basis functions can be used to closely approximate the behavior of the solution over a range of values of alpha.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Related Data and Programs:

CASE1_FLOW is a collection of solutions to a flow problem.

CAVITY_FLOW is a collection of solutions to flow in a cavity.

CVT_BASIS_FLOW is an interactive executable FORTRAN90 program which can be used to analyze this data, and compute a small set of "basis vectors" using CVT techniques.

INOUT_FLOW is a collection of solutions to flow in the "inout" region.

INOUT_FLOW2 is a collection of solutions to flow in the "inout" region.

POD_BASIS_FLOW is an interactive executable FORTRAN90 program which can be used to analyze this data, and compute a small set of "basis vectors" using POD techniques.

TCELL is a FORTRAN77 program for solving a time dependent Navier Stokes problem in a T-cell region.

The TCELL_FLOW_MOVIE is an MP4 animation of the data in this directory.

TRIANGULATION_PLOT is a FORTRAN90 program which can be used to draw an image of the nodes and elements used in the triangulation of the region.

VECTOR_PLOT is a FORTRAN90 program which can be used to draw an image of the velocity vector field over the region.

Reference:

• John Burkardt, Max Gunzburger, Hyung-Chun Lee,
  Centroidal Voronoi Tessellation-Based Reduced-Order Modelling of Complex Systems,
  SIAM Journal on Scientific Computing,
  Volume 28, Number 2, 2006, pages 459-484.

Datasets:

• xy.txt, the XY coordinates associated with the nodes.
• elements.txt, a grouping of the nodes into 6 node quadratic finite elements.
• steady.txt, the steady state velocity field.
• tcell_grid.png, a PNG image of the grid.
• tcell_flow.png, a PNG image of the steady state velocity field, created by VECTOR_PLOT.
• tcell_flow_direction.png, a PNG image of the steady state vector direction field, created by VECTOR_PLOT.

TCELL_FLOW_SNAPSHOT can display the flow data from a single timestep.

TCELL_FLOW_MOVIE can animate the flow data from a sequence of timesteps.

The following files contain the velocity vectors at the 500 successive timesteps computed by the finite element simulation.

• up001.txt.
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You can go up one level to the DATASETS directory.