Demos / Gallery

i1 U 0p1 Re700 SPHERE planes bis

Precession in a full sphere

Rotation angle=120, precession rate=0.3;
first bifurcation towards a steady state with an S-shape vortex (=spinover mode or Poincare flow) at Re=700, shown by an isosurface of |U| and slices of U_z. The wireframe shows the spatial domain decomposition used in the SFEMANS code (two meridional domains that are not strictly hemispherical, and with 48 azimuthal modes).

R. Hollerbach, C. Nore, P. Marti, S. Vantieghem, F. Luddens and J. Léorat.

 

i2 Ext2 J2 100 jz LdcB RotU zmoins

Dynamo in a precessing cylinder

Rotation angle=90, precession rate=0.15, aspect ratio H/R=2. Snapshot for Re = 1200, Rm = 2400 showing vorticity field lines (red), magnetic energy colored by the vertical component of the current and magnetic field lines colored by the axial component (yellow/green for positive/negative Hz component).

C. Nore, J. Léorat, J. L. Guermond and F. Luddens.

 

 

i4 merg

 

Merging of two helical vortices at various helical pitch values.

Temporal sequence showing the helical component of vorticity in a plane normal to the helix axis. Top: diffusive merging at order 1 pitches. Bottom: merging due to Okulov's instability at small pitch.

I. Delbende, M. Rossi and B. Piton.

 

 

 

i5 RotDiskManipi5 RotDiskBlue Deformation of a free surface driven by a rotating disk: experiment and simulation (Blue)

Deformation of a free surface driven by a rotating disk: comparison between numerical simulation (using the code Blue) and experiment conducted at LIMSI in the laminar axisymmetric regime. Large deformation regime (compared to the fluid depth at rest). Radius: 62.5mm, fluid depth at rest (15-60 mm), fluid: 50 mPa.s, density 866 kg/m3), rotation rate 100-200 rpm.

L. Martin Witkowski, J. Chergui and Lyes Kahouadji.

 

i6 tooth

 

 

Edge state in a Blasius boundary layer

Isosurfaces of the streamwise velocity and of the lambda2 vortex criterion.

Spectral DNS.

Y. Duguet, P. Schlatter, D.S. Henningson and B. Eckhardt.

 

 

Stokes drift

i7 compil wietze

A particle in an undulatory flow ((a) star) can have a net motion ((a) dashed line). Inside an electrically conducting liquid this net motion can generate a magnetic field via a dynamo effect. We show theoretically and numerically that the Stokes drift associated with the wave produces the same type of magnetic field (c) that the initial wave (b). Calculation of the Stokes drift of the wave predicts directly whether it can behave as a dynamo.

W. Herreman and P. Lesaffre