A Bound on Ekman Pumping

Ekman pumping in compact astrophysical bodies

We examine the dynamics of a rotating viscous fluid following an abrupt change in the angular velocity of the solid bounding surface. We include the effects of a density stratification and compressibility which are important in astrophysical objects such as neutron stars. We confirm and extend the conclusions of previous studies that stratification restricts the Ekman pumping process to a relat...

Internally by Radiation and Entrainment Wind Stress Leads to Ekman Pumping Ekman Pumping Quasi - Geostrophic Dynamics Quasi

Dissipative Energization of Baroclinic Waves by Surface Ekman Pumping

A two-layer quasi-geostrophic model is used to study the effect of lower boundary Ekman pumping on the energetics of baroclinic waves. Although the direct impact of the Ekman pumping is to damp the total eddy energy, either the eddy available potential energy (EAPE) or the eddy kinetic energy (EKE), individually, can grow due to the Ekman pumping. Growth of EAPE is favored if the phase differen...

Helical magnetorotational instability in a Taylor-Couette flow with strongly reduced Ekman pumping.

The magnetorotational instability (MRI) is thought to play a key role in the formation of stars and black holes by sustaining the turbulence in hydrodynamically stable Keplerian accretion disks. In previous experiments the MRI was observed in a liquid metal Taylor-Couette flow at moderate Reynolds numbers by applying a helical magnetic field. The observation of this helical MRI (HMRI) was inter...

Interaction between Ekman pumping and the centrifugal instability in Taylor–Couette flow

The endwalls in a Taylor–Couette cell introduce adjacent boundary layers that interact with the centrifugal instability. We investigate the interaction between the endwall Ekman layers and the Taylor vortices near transition from nonvortical to vortical flow via direct numerical simulation using a spectral method. We consider a radius ratio of h50.75 in a short annulus having a length-to-gap ra...