The Coursier Dam sinkholes: a case study of backward erosion as a consequence of filter incompatibility: (Abstract)

Contribution for assessing filter efficiency in zoned dams: (Paper and Abstract)

Dam filters are mainly designed using filter criteria based on the grain size distribution. The main design criteria against which performance is assessed are a criterion for retention of fine particles. The characteristic size of finer fraction influences the size distribution of the filter pore and hence the retention capacity of flowing...

A Dynamic Subfilter-scale Stress Model for Large Eddy Simulations Based on Physical Flow Scales

We propose a new definition of the length scale in an eddy-viscosity model for large-eddy simulations (LES). This formulation extends and generalizes a previous proposal [Piomelli, Rouhi and Geurts, Proc. ETMM10, 2014], in which the LES length scale was expressed in terms of the integral length-scale of turbulence determined by the flow...

Planar velocity & concentration measurements in a magnetic micromixer with interface front detection

Mixing is often a challenge in small scales and substantial research effort is focused on designing high performance micromixers. Active micromixers use various forces to enhance mixing efficiency. Among these, magnetic forces are often preferred as they are non-contact and do not require manufacturing of small moving parts in the microchannel....

Filtered gas-solid momentum transfer models

To account for meso-scale phenomena in coarse grid simulations, correlation terms appearing in the filtered gas-solid flow equations have to be modeled. Filtered models for the gas-solid momentum transfer are focused on. The latter consists of the drag force on the one hand and the distribution of the gas phase pressure gradient over the phases...

Preconditioning applied to Eulerian-Eulerian gas-solid flow calculations with variable gas density

Local preconditioning for Eulerian-Eulerian gas-solid flow calculations with variable gas density is investigated. The performance of simultaneous solution algorithms for low-Mach calculations is strongly related to preconditioning. The gas-solid drag source terms are at the origin of a solid volume fraction and frequency dependency of the...

Numerical investigation of the aerodynamic noise from a forward-facing step

In the present study, aerodynamic noise from a forward-facing step is numerically investigated for Reynolds number based on the step height, Reh=8,000 and flow Mach number, M=0.03. A three-dimensional flow over the forward-facing step is calculated by the incompressible large eddy simulation (LES), while its acoustic field is solved by the...

Use of explicit filtering, second-order scheme and SGS models in LES of turbulent flow

In large eddy simulations (LES) using low-order finite-difference-type methods, the numerical error can be large in comparison to the effect of the sub-grid scale (SGS) model. In this paper, we study two approaches to explicit filtering which can reduce the numerical error involved. In the first approach, the non-linear convection term of the...

Magnitude control of commutator errors

Non-uniform filtering of the Navier-Stokes equations expresses itself, next to the turbulent stresses, in additional closure terms known as commutator errors. These terms require explicit subgrid modeling if the non-uniformity of the filter is sufficiently pronounced. We derive expressions for the magnitude of the mean flux, the turbulent stress...