Relativistic Turbulence provides an alternative to internal shocks as a mechanism for producing GRBs’ variable light curves with efficient conversion of energy to radiation. In this model the relativistic outflow is broken into small eddies moving relativistically in the outflow’s rest frame. Variability arises because an observer sees an eddy only when its velocity points towards him and only ...

The paper presents an implementation of a one-equation turbulence model with 3-D adaptive hybrid grids. The grids are composed of prismatic elements close to the body surface, and tetrahe-dral elements elsewhere. An adaptive redistribution scheme is also presented which results in increased resolution of boundary layers and wakes. Use of prisms is extended to resolve both single and multiple wa...

Profiles of the index of refraction structure parameter (Cn2), as well as inner and outer scales of turbulence, are of high importance to estimate and predict the channel behavior characterizing satellite to ground optical links. The Cn2 HufnagelValley model is up to date the most commonly used one due to its simplicity and relative accuracy. However, it can be quite inadequate especially for g...

of turbulence models for shear ows by a double expansion technique," Phys. Fluids \Conservation laws and two ux spectra of hydro-dynamic convective turbulence," Physica D 57 (1992). 15 Bolgiano and Kolmogorov scaling are believed to occur together in general ows; this suggests that the general dissipation rate model could combine the results for both scalings as in Eq. (40). 2 However, a comple...

To investigate hydrodynamic performance of the end cover under different inclined angles, a series of 3-Dimensional geometric models of the end cover with different inclined angles were built by Creo. The maximum inclined angle is 32 degrees and the minimum is 6 degrees. Numerical simulations by solving the Navier-Stokes equation, coupled with the “k-ɛ” turbulence model, were carried out. At la...

The flow solver, UBIFLOW, was developed with the goal of producing efficient, accurate flow solution software capable of handling complex configurations. In the work presented here, UBIFLOW’s ability to simulate the flowfield of complex configurations was tested on a couple of launch vehicles. The predictive capability of UBIFLOW was demonstrated through the use of sample launch configurations ...

Abstract. Three-dimensional transonic flow over a delta wing is investigated using several turbulence models. The performance of linear eddy viscosity models and an explicit algebraic stress model is assessed at the start of vortex flow, and the results compared with experimental data. To assess the effect of transition location, computations that either fix transition aft of the leading edge o...

The turbulent dispersion of non-evaporating droplets in an axisymmetric round jet issuing from a nozzle is investigated both experimentally and theoretically. The experimental data set has a well-defined inlet boundary with low turbulence intensity at the nozzle exit, so that droplet dispersion is not affected by the transport of nozzle-generated fluctuating motion into the jet, and is influenc...

The present investigation concerns the development of advanced scalar turbulence modeling approaches and their application to the calculation of non-isothermal wall-bounded flow phenomena. A new scalar modeling technique based on scalar turbulent scales is proposed and implemented at a second-order modeling approach. Instead of the classical analogy concept between the mechanical and the scalar...

In this paper, the continuous adjointmethod to compute shape sensitivities in aerodynamic designwith turbulence modeling is described and developed. The focus is on compressible flows described by the Reynolds-averaged Navier–Stokes equations and the classical Spalart–Allmaras model for turbulence. Turbulence modeling usually requires, in particular, computation of the distance to the surface. ...