Phase diagram of turbulent Taylor-Couette flow

We will present the results of our recent numerical work on the nature of the phase diagram of turbulent Taylor-Couette (TC) flow, both with co- and counterrotating cylinder. The work can be seen as the extension of the famous experimental Andereck et al. phase diagram for Taylor-Couette flow just above the onset of instabilities, towards the...

Geostrophic convective turbulence: The effect of boundary layers

We conduct computations of rotating Rayleigh-Bénard convection in the so-called geostrophic regime, characterized by strong thermal forcing (high Rayleigh numbers) and strong rotation (small Ekman numbers). We employ the full Navier-Stokes equations in our computations and compare no-slip and stress-free boundaries for the plates. The Ekman...

Bulk statistics of stable and decaying Taylor-Couette turbulence

In this talk we focus on the velocity fluctuations in highly turbulent Taylor-Couette flow for the case of stable flow (constant rotation) and for decaying flow. Turbulent flows are generally characterized by the range of scales of their fluctuations, and a statistical description of the flow is often done by calculating the correlations of...

Measurements of small radius ratio turbulent Taylor-Couette flow

In Taylor-Couette flow, the radius ratio ($\eta = r_i/r_o$) is one of the key parameters of the system. For small $\eta$, the asymmetry of the inner and outer boundary layer becomes more important, affecting the general flow structure and boundary layer characteristics. Using high-resolution particle image velocimetry we measure flow profiles...

Direct numerical simulation of turbulent Taylor-Couette flow with grooved walls

We present direct numerical simulations of Taylor-Couette flow with grooved walls up to inner cylinder Reynolds number of $Re_i=3.76\times10^4$, corresponding to Taylor number of $Ta=2.15\times10^9$. The simulations are performed at a fixed radius ratio $\eta=r_i/r_o=0.714$. The grooves are axisymmetric V-shaped obstacles attached to the wall...

Direct Numerical Simulations of two-phase Taylor-Couette turbulence

Two-phase Taylor-Couette flow is simulated using the Euler-Lagrange approach, where the dispersed phase is treated as point particles with effective forces such as drag, lift, added mass and buoyancy acting on them. Two-way coupling is implemented between the carrier and the dispersed phase allowing us to study the interaction between the point...

Dynamics of finite-sized light spheres in turbulence

We report experimental results on the Lagrangian dynamics of finite-size light particles in turbulence. Using an orthogonal camera setup and 3D particle tracking, we study the velocity and acceleration statistics of rigid light spheres in a water tunnel with nearly homogeneous and isotropic turbulence. The Reynolds number (ReY) is varied from...

Double diffusive convection between two parallel plates with different boundary conditions

We investigate the double diffusive convection between two parallel plates with either no-slip or free-slip boundary conditions. Direct numerical simulations have been conducted systematically for a series of control parameters. Salt fingers can be observed for both boundary conditions and all parameters explored. Compared to the no-slip case,...