Mach wave radiation from supersonic jets is revisited to better quantify the extent to which linearized equations represent the details of the actual mechanism. To this end, we solve the linearized Navier–Stokes equations ~LNS! with precisely the same mean flow and inflow disturbances as a previous direct numerical simulation ~DNS! of a perfectly expanded turbulent M51.92 jet @Freund et al., AI...

A pore-scale description of species and charge transport through a bilayer cathode catalyst layer CL of a polymer electrolyte fuel cell using a direct numerical simulation DNS model is presented. Two realizations of the bilayer catalyst layer structure are generated using a stochastic reconstruction technique with varied electrolyte and void phase volume fractions. The DNS calculations predict ...

The atomization of fuel jets in car or plane engines involves complex process with multiphase motions and turbulent flow regimes in a highly coupled way. The Direct Numerical Simulation (DNS) of interfacial flows is investigated in order to characterize the coupling between turbulent flow structures and interface deformations occurring during atomization of a liquid sheet. An incompressible Gho...

Stochastic Lagrangian models for the velocity following a fluid particle are used both in studies of turbulent dispersion and in probability density function ~PDF! modeling of turbulent flows. A general linear model is examined for the important case of homogeneous turbulent shear flow, for which there are recent direct numerical simulation ~DNS! data on Lagrangian statistics. The model is defi...

Mathematical modeling plays an important role whenever flow investigations are performed. In this paper special emphasis was given to models which are used in turbulent flow simulations and the effect of numerical discretization. The numerical scheme is of great importance when direct numerical simulations, i.e. the solution of the Navier-Stokes equations without any additional turbulence model...

An immersed-boundary method was employed to perform a direct numerical simulation (DNS) of flow around a wall-mounted cube in a fully developed turbulent channel for a Reynolds number Re = 5610, based on the bulk velocity and the channel height. Instantaneous results of the DNS of a plain channel flow were used as a fully developed inflow condition for the main channel. The results confirm the ...

In this study, the effect of limited spatial resolution of hot wire anemometry (HWA) is investigated through analysis of the two dimensional energy spectra from direct numerical simulation (DNS) of turbulent channel flow at Reτ ≈ 934. Various spanwise filter lengths are applied to the streamwise velocity component in order to mimic the spatial resolution of the HWA experiments. The overall effe...

The state-of-the-art for Direct Numerical Simulation (DNS) of boiling multiphase flows is reviewed, focussing on potential of available computational techniques, the level of current success for their applications to model several basic flow regimes (film, pool-nucleate and wall-nucleate boiling – FB, PNB and WNB, respectively). Then, we discuss multiphysics and multiscale nature of practical b...

Abstract. We carry out direct numerical simulation (DNS) of turbulent flow in pipes with a grit-blasted surface, to investigate both on momentum and heat transfer. A wide range Reynolds numbers are considered, while maintaining constant molecular Prandtl number 0.7. The large relative roughness influences the velocity temperature fields, indicating that analogy does not hold at high bulk number.

The objective of this work was to investigate the influence of preferential diffusion on flame structure and propagation of lean-premixed hydrogen-carbon monoxide syngas-air flame at elevated pressure using direct numerical simulation (DNS) and detailed chemistry. The physical problem investigated is lean-premixed H2/CO outwardly propagating turbulent spherical flame at constant pressure of 4ba...