1. Vasileios Vlachakis 03/05/2006
Numerical Investigation of turbulence characteristics in a tank agitated by a Rushton impeller
Vasileios Vlachakis
03/05/2006

2. Computational Grid The computational grid consists of 450,000 cells
Grid surrounding the impeller (The unsteady Navier - Stokes equations are solved)
Outside grid (The steady Navier - Stokes equations are solved)
View from the top
3Dimensional View

3. Normalized Radial velocity
The flow can be described as
A radial jet with two recirculation
regions in each side of the tank
The coordinate axis have been
normalized with the tank diameter
while the radial velocity with the
tip velocity (Utip)
Contour plot of the radial velocity superimposed with streamlines

4. Normalized Z-Voricity
The figure shows a slice on the
Z plane exactly at the height
of the impeller (z=0)
The trailing vortices behind the
blades can be seen as well as
the vortices that form behind
the baffles
Contour Plot of the z vorticity superimposed with Streamlines

5. Streamlines in different slices
Streamlines at
Streamlines at

6. Y- Vorticity Trailing Vortices at y/Dtank=0.167
(exactly at the end of the blades)
Trailing vortices at the 1st blade
Trailing vortices at the next blade

7. Iso Z-Vorticity around
the impeller
Z isovorticity behind the baffle

8. Turbulent Kinetic Energy
Non dimensionalized TKE
at the impeller plane (z=0)
Non dimensionalized TKE
at x=0 slice

9. Normalized Dissipation Rate
Normalized Dissipation rate at blade plane
Normalized Dissipation rate at plane
Between two blades (30 degrees angle)

10. Dissipation rate in the entire tank
As we show in the previous slide
the dissipation rate has its maximum
value at the end of the blades but it
has a high value near the baffles
where the radial jet impinges on the
wall

11. Iso surface of helicity