Dispersed two-phase flows often involve interfacial activities such as chemical reaction and phase change, which couple the fluid dynamics with heat and mass transfer. As a step toward understanding such problems, we numerically simulate the sedimentation of solid bodies in a Newtonian fluid with convection heat transfer. The two-dimensional Navier–Stokes and energy equations are solved at mode...

Roll clouds and associated roll convection, are fairly common features of the atmospheric boundary layer. While these organized cumuliform clouds are found over many regions of the planet, they are quite ubiquitous near the edge of the polar ice sheets. In particular, during periods of off-ice flow, when cold polar air flows from the ice pack over the relatively warm ocean water, strong boundar...

We combine the finite element method with the Eulerian–Lagrangian Localized Adjoint Method (ELLAM) to solve the convection–diffusion equations that describe the kinematics of magnetohydrodynamic flows, i.e., the advection and diffusion of a magnetic field. Simulations of three two-dimensional test problems are presented and in each case we analyze the energy of the magnetic field as it evolves ...

The noninvasive investigation of flows, where media of different optical density participate, is often not possible. A measurement through dynamic water-air surfaces will result in higher measurement uncertainties or they will hinder any measurement at all. To overcome this issue we make use of adaptive optics (AO). Dependent on the measurement system, an adaptive correction of the illumination...

A sequence of direct simulations is used to study mechanisms for the growth of secondary circulations and turbulence in stratified shear flows. Five cases are examined, of which four deliver Holmboe waves as the primary instability and the fifth generates Kelvin-Helmholtz billows. Secondary circulations range in strength from weak, laminar motions to turbulence that destroys the parent wave. Pr...

In the outer envelope of the Sun and in other stars, differential rotation and meridional circulation are maintained via the redistribution of momentum and energy by convective motions. In order to properly capture such processes in a numerical model, the correct spherical geometry is essential. In this paper I review recent insights into the maintenance of mean flows in the solar interior obta...

We continue the description of a lowMach number hydrodynamics algorithm for reacting, full star flows. Here we demonstrate how to accurately incorporate reactions using a second-order accurate Strang-splitting technique. We also improve the fidelity of the model by allowing the base state to evolve in response to large-scale convection as well as large-scale heating, taking care to account for ...

Cell based microassays allow the screening of a multitude of culture conditions in parallel, which can be used for various applications from drug screening to fundamental cell biology research. Tubeless microfluidic devices based on passive pumping are a step towards accessible high throughput microassays, however they are vulnerable to evaporation. In addition to volume loss, evaporation can l...

We perform helioseismic holography to assess the noise in p-mode travel-time shifts which would form the basis of inferences of large-scale flows throughout the solar convection zone. We also derive the expected travel times from a parameterized return (equatorward) flow component of the meridional circulation at the base of the convection zone from forward models under the assumption of the ra...

This article surveys the development of observational understanding of the interior rotation of the Sun and its temporal variation over approximately forty years, starting with the 1960s attempts to determine the solar core rotation from oblateness and proceeding through the development of helioseismology to the detailed modern picture of the internal rotation deduced from continuous helioseism...