For the purpose of understanding fingering patterns, we propose a simple model system composed of splitting elements where we regard a tip of each finger as a basic dynamical unit. Numerical simulations of the model reproduce turbulent states, fractal and tree-like structures and spatiotemporal intermittency which are all quite similar in behavior to real systems. keywords: fingering patterns, ...

In this paper we look at a number of approaches for modeling the system acquisition process. Beginning with the waterfall model of Winston Royce, we continue with derivation that includes more intricate and detailed waterfall models with feedback, including the “V” and spiral models. In addition we look at several acquisition strategies. In reviewing the various models we discuss our view that ...

The probability distribution function of plasma density fluctuations at the edge of fusion devices is known to be skewed and strongly non-Gaussian. The causes of this peculiar behavior are, up to now, largely unexplored. On the other hand, understanding the origin and the properties of edge turbulence is a key issue in magnetic fusion research. In this paper we show that a stochastic fragmentat...

Four classes of turbulence models (algebraic, k − , k − ω and a differential Reynolds-stress model) are applied to boundary layers under adverse pressure gradient with a constant equilibrium parameter β = δ * τ w dp dx. Numerical solutions up to Re θ = 10 8 give the classical scalings in the inner and outer layer for all models. Comparison is made with experiments of Clauser at β ≈ 2 and 8 and ...

Gravity currents are very common in nature and may appear in rivers, lakes, oceans, and the atmosphere. They are produced by the buoyant forces interacting between fluids of different densities and may introduce sediments and pollutants into water bodies. In this study, the hydrodynamics and propagation of gravity currents are investigated using WISE (Width Integrated Stratified Environments), ...

Nomenclature a w speed of sound at wall (m/s) D diameter (m) H AW adiabatic enthalpy (J/kg) H w wall enthalpy (J/kg) H 0 total enthalpy (J/kg) h heat transfer coefficient (kg/m 2 /sec), h FR Fay-Riddell heat transfer coefficient (kg/m 2 /sec) M ∞ free stream Mach number M e boundary layer edge Mach number p ∞ free stream pressure (N/m 2) q heat transfer rate (W/m 2) r radial position (m) R base...

in this paper, the accuracy of k- and k- turbulence models in super sonic boundary layer capturing of smooth/rough flat plates have been comprehensively investigated. among these investigations, some sorts of sensitivity analysis, including change in turbulence model, generated-grid density, near wall affects, c magnitude (for boundary layers generated on smooth flat plates), and change in c...

a full scale physical model of a thin slab caster with a four-hole design submerged entry nozzle (sen) was constructed. on the basis of the dimensionless reynolds and froude similitude criteria, the fluid flow in a full-scale model is similar to that of the actual system and, hence, the data obtained from the water model can be applied to the actual system. in order to determine the optimum ope...

2D homogeneous turbulence is relevant to geophysical turbulence on large horizontal scales because of the thinness of Earth’s atmosphere and ocean (i.e., H/L 1) and Earth’s rotation (i.e., Ro 1) and stable stratification (i.e., Fr 1), both of which tend to suppress vertical flow and make the 2D horizontal velocity component dominant. A detailed explanation for this involves the theory for geost...