Despite their well-known limitations, Reynolds averaged Navier-Stokes (RANS) models remain the most commonly employed tool for modeling turbulent flows in engineering practice. RANS are predicated on solution of equations, but equations involve an unclosed term, stress tensor, which must be modeled. The tensor is often modeled as algebraic function mean flow field variables and turbulence varia...

Acoustic Doppler current profilers (ADCP) are widely used in geophysical studies for mean velocity profiling and calculation of energy dissipation rate. On the other hand, estimation turbulent stresses from ADCP data still remains challenging. With four-beam version device, only two shear derivable; even five-beam (Janus+), full Reynolds stress tensor is problematic currently. The known attempt...

Gas-phase velocity fluctuations in fixed particle beds and freely evolving suspensions are quantified using particle-resolved direct numerical simulation (PR-DNS). The flow regime corresponds to homogeneous gas-solid systems typically encountered in fluidized bed risers, with high solid to gas density ratio and particle diameter being greater than the dissipative length scales. The contribution...

OBJECTIVE Laminar flow becomes disturbed at high velocities, reducing shear stress and augmenting vascular inflammation and proliferation, processes that are pivotal in restenosis and atherogenesis. We hypothesized that disturbed blood flow after coronary angioplasty is associated with adverse long-term clinical outcome. METHODS AND RESULTS The cineangiograms from 97 patients undergoing laser...

This paper provides a multiscale analytical study of steady incompressible turbulent flow through a channel of either Couette or pressure-driven Poiseuille type. Mathematically, the paper’s two most novel features are that (1) the analysis begins with an underdetermined singular perturbation problem, namely the Reynolds averaged mean momentum balance equation, and (2) it leads to the existence ...

We revisit the Germano-identity error in the dynamic modeling procedure in the sense that the current modeling procedure to obtain the dynamic coefficient may not truly minimize the error in the mean and global sense. A “corrector step” to the conventional dynamic Smagorinsky model is proposed to obtain a corrected eddy viscosity which further reduces the error. The change in resolved velocity ...

[1] In this paper we consider the problem of modeling a turbulent pulsating boundary layer over ripples. We compare the results of two modeling strategies, Wilcox’s k w Reynolds-Averaged Navier-Stokes equations (RANS) and large-eddy simulation (LES) employing the Lagrangian dynamic eddy viscosity model. The geometry and parameters employed are relevant to nearshore oceanic flows, and the result...