We include Smagorinsky's algebraic eddy viscosity approach into the multiple-relaxation-time (MRT) lattice Boltzmann equation (LBE) for large-eddy simulations (LES) of turbulent flows. The main advantage of the MRT-LBE model over the popular lattice BGK model is a significant improvement of numerical stability which leads to a substantial reduction of oscillations in the pressure field, especially for turbulent flow simulations near the numerical stability limit. The MRT-LBE model for LES is validated with a benchmark case of a surface mounted cube in a channel at Re = 40 000. Our preliminary results agree well with experimental data.

Large-Eddy Simulations with a Multiple-Relaxation-Time LBE Model

Metabolic variability in bioprocessing: implications of microbial phenotypic heterogeneity

The trajectories, referred to as lifelines, of individual microorganisms in an industrial scale fermentor under substrate limiting conditions were studied using an Euler-Lagrange computational fluid dynamics approach. The metabolic response to substrate concentration variations along these lifelines provides deep insight in the dynamic environment inside a large-scale fermentor, from the point of view of the microorganisms themselves. We present a novel methodology to evaluate this metabolic response, based on transitions between metabolic "regimes" that can provide a comprehensive statistical insight in the environmental fluctuations experienced by microorganisms inside an industrial bioreactor. These statistics provide the groundwork for the design of representative scale-down simulators, mimicking substrate variations experimentally. To focus on the methodology we use an industrial fermentation of Penicillium chrysogenum in a simplified representation, dealing with only glucose gradients, single-phase hydrodynamics, and assuming no limitation in oxygen supply, but reasonably capturing the relevant timescales. Nevertheless, the methodology provides useful insight in the relation between flow and component fluctuation timescales that are expected to hold in physically more thorough simulations. Microorganisms experience substrate fluctuations at timescales of seconds, in the order of magnitude of the global circulation time. Such rapid fluctuations should be replicated in truly industrially representative scale-down simulators.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/elsc.201600061

Euler‐Lagrange computational fluid dynamics for (bio)reactor scale down: An analysis of organism lifelines

Apoptosis: A mammalian cell bioprocessing perspective.

https://cyberleninka.org/article/n/729422.pdf

Euler-Lagrange analysis towards representative down-scaling of a 22 m3 aerobic S. cerevisiae fermentation

CFD-based compartment model for description of mixing in bioreactors

Some structural and hydrodynamic properties of RCM-NCX-1116, a Ni–Cr metallic foam packing manufactured by Recemat International B.V (The Netherlands) are investigated using X-ray radiography and X-ray micro-tomography. Local values of porosity and pore diameters are measured on a foam sample 3D image obtained with a Skyscan-1172 high-resolution desk-top micro-CT system operated at 100 kV. Structural parameters computed on tomography images agree well with manufacturer data. Hydrodynamic tests are performed in a flat rectangular column packed with a sheet of metallic foam packing. Measurements are realized with a single-phase flow of liquid as well as with a counter-current flow of gas and liquid. Dynamic and static liquid holdup distributions and liquid radial spreading coefficient are measured on 2D radiographic images of the bed obtained with the high energy large scale ULG 420 kV scanner operated in the radiographic mode at 420 kV. Pressure drop measurements are successfully compared to experimental results reported in literature, as well as to the literature model predictions and to values computed using an in-house Lattice Boltzmann CFD simulation code.

Phase distribution measurements in metallic foam packing using X-ray radiography and micro-tomography

Gas flow simulations in a structured packing by lattice Boltzmann method

In this work, we study the conditions needed to reach homogeneous distribution of aluminium salts particles in water inside a torispherical bottom shaped stirred tank of 70 L equipped with a Pfaudler RCI type impeller and three equispaced vertical baffles. The aim of the present study is to develop a CFD model describing the quality of particle distribution in industrial scale tanks. This model, validated with experimental data, is used afterwards to develop scale-up and scale-down correlations to predict the minimum impeller speed needed to reach homogeneous solid distribution Nhs. The commercial CFD software Fluent 14 is used to model the fluid flow and the solid particle distribution in the tank. Sliding Mesh approach is used to take the impeller motion into account. Assuming that the discrete solid phase has no influence on the continuous liquid phase behaviour, the fluid flow dynamics is simulated independently using the well-known k-∊ turbulence model. The liquid-solid mixture behaviour is then desc...

https://journals.sagepub.com/doi/pdf/10.1155/2013/329264

Sébastien Calvo

Papers

CFD-based compartment model for description of mixing in bioreactors

Phase distribution measurements in metallic foam packing using X-ray radiography and micro-tomography

Gas flow simulations in a structured packing by lattice Boltzmann method

Experimental Characterisation and Modelling of Homogeneous Solid Suspension in an Industrial Stirred Tank

Hydrodynamics in a disposable rectangular parallelepiped stirred bioreactor with elliptic pendulum motion paddle