We propose a new approach for analyzing multi-scale properties of the atmospheric flow that employs the recently introduced isentropic streamfunction and relies on its scale decomposition with Haar wavelets. We applied this method to a cloud resolving simulation of a planetary Walker Cell characterized by pronounced multi-scale flow. The resulting set of isentropic streamfunctions – obtained at...

Existing experimental and theoretical studies are discussed which lead to the clear hypothesis of a hitherto unidentified convective instability mode that dominates within the boundary-layer flow over slender rotating cones. The mode manifests as Görtlertype counter-rotating spiral vortices, indicative of a centrifugal mechanism. Although a formulation consistent with the classic rotating-disk ...

Abstract. We propose and develop a functional minimization weak-formulation treatment of possibly complex applied input/output conditions which handles either convective, adiabatic, or prescribed temperature at the entrance or the exit of parallel convective exchangers. This formulation permits to re-cast realistic three-dimensional exchangers into a two-dimensional eigenvalue problem which is ...

We present the results of a very large aspect ratio (A = 42.6) numerical simulation of fully compressible turbulent convection in a polytropic atmosphere, and focus on the properties of large-scale flows. Mesoscale patterns dominate the turbulent energy spectrum. We show that these structures, which had already been observed in Boussinesq simulations by Cattaneo et al. (2001), have a genuine co...

The global electrostatic mode in pair-ion plasmas is discussed for cylindric geometry and for a radially inhomogeneous equilibrium density. In the case of a Gaussian radial density profile, exact analytical eigen solutions are found in terms of the Kummer confluent hypergeometric functions. The mode is identified as a convective cell propagating in the poloidal and axial direction, having at th...

Excitation of solar-like oscillations is attributed to turbulent convection and takes place at the upper-most part of the outer convective zones. Amplitudes of these oscillations depend on the efficiency of the excitation processes as well as on the properties of turbulent convection. We present past and recent improvements on the modeling of those processes. We show how the mode amplitudes and...

We consider the stability of a compressible shear flow separating two streams of different speeds and temperatures. The velocity and temperature profiles in this mixing layer are hyperbolic tangents. The normal mode analysis of the flow stability reduces to an eigenvalue problem for the pressure perturbation. We briefly describe the numerical method that we used to solve this problem. Then, we ...

We analyze the stability of g-modes in variable white dwarfs with hydrogen envelopes. All the relevant physical processes take place in the outer layer of hydrogen rich material which consists of a radiative layer overlain by a convective envelope. The radiative layer contributes to mode damping because its opacity decreases upon compression and the amplitude of the Lagrangian pressure perturba...

We present the first spontaneous sequence of hydrodynamic instabilities due to the evolution of the convective flow from the rest state toward chaos in an anisotropic fluid : a nematic liquid crystal subjected to an AC electric field. The resulting structures are of decreasing symmetry as the control parameter is gradually increased. The study of the streamlines allows the interpretation of the...

In this paper an attempt is made to evaluate the convective mass transfer coefficient during drying of jaggery in a controlled environment. In this method, different masses of jaggery were used. The jaggery was dried in the roof type even span greenhouse with a floor area of 1.2x0.8 m in natural and forced convection mode at atmospheric pressure till it attained almost no variation in mass. The...