Application of a Fractional-Step Method to Incompressible Navier-Stokes Equations

Preface Part I. Turbulence: 1. Introduction 2. Coherent structures 3. Proper orthogonal decomposition 4. Galerkin projection Part II. Dynamical Systems: 5. Qualitative theory 6. Symmetry 7. One-dimensional 'turbulence' 8. Randomly perturbed systems Part III. 9. Low-dimensional Models: 10. Behaviour of the models Part IV. Other Applications and Related Work: 11. Some other fluid problems 12. Review: prospects for rigor Bibliography.

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Turbulence, Coherent Structures, Dynamical Systems and Symmetry

A spectral element method for fluid dynamics: Laminar flow in a channel expansion

Laser-Doppler measurements of velocity distribution and reattachment length are reported downstream of a single backward-facing step mounted in a two-dimensional channel. Results are presented for laminar, transitional and turbulent flow of air in a Reynolds-number range of 70 < Re < 8000. The experimental results show that the various flow regimes are characterized by typical variations of the separation length with Reynolds number. The reported laser-Doppler measurements do not only yield the expected primary zone of recirculating flow attached to the backward-facing step but also show additional regions of flow separation downstream of the step and on both sides of the channel test section. These additional separation regions have not been previously reported in the literature.Although the high aspect ratio of the test section (1:36) ensured that the oncoming flow was fully developed and two-dimensional, the experiments showed that the flow downstream of the step only remained two-dimensional at low and high Reynolds numbers.The present study also included numerical predictions of backward-facing step flow. The two-dimensional steady differential equations for conservation of mass and momentum were solved. Results are reported and are compared with experiments for those Reynolds numbers for which the flow maintained its two-dimensionality in the experiments. Under these circumstances, good agreement between experimental and numerical results is obtained.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022112083002839

Experimental and Theoretical Investigation of Backward-Facing Step Flow

The dynamic subgrid-scale (SGS) model of Germano et al. (1991) is generalized for the large eddy simulation (LES) of compressible flows and transport of a scalar. The model was applied to the LES of decaying isotropic turbulence, and the results are in excellent agreement with experimental data and direct numerical simulations. The expression for the SGS turbulent Prandtl number was evaluated using direct numerical simulation (DNS) data in isotropic turbulence, homogeneous shear flow, and turbulent channel flow. The qualitative behavior of the model for turbulent Prandtl number and its dependence on molecular Prandtl number, direction of scalar gradient, and distance from the wall are in accordance with the total turbulent Prandtl number from the DNS data.

A dynamic subgrid‐scale model for compressible turbulence and scalar transport

Design and construction of aeration systems for optimum operation of large wastewater treatment plants

The invention relates to a method for the combustion of liquid fuel (F), especially oil, wherein the liquid fuel (F) is distributed by means of a distribution device (1) and directed to a downstream reactor with porous means (6) having a communicating pore volume, whose Peclet number allows for flame expansion and full combustion of the liquid fuel (F) inside the porous means (6).

Method and device for the combustion of liquid fuel

That paper is devoted to the analysis of the importance of the finite size of the laser beam on the quality of bubble measurements by a Phase Doppler Anemometer (PDA) (trajectory ambiguity or Gaussian beam effect). Detection at 30 ° and 70° are studied for a standard PDA, a non-standard PDA and dual burst configurations. The possibility to sort bubbles and perfectly reflecting particles is discussed.

Measurement of bubbles by Phase Doppler technique and trajectory ambiguity

Developments in Laser Techniques and Fluid Mechanics

This paper describes the numerical investigations carried out by LSTM within the TRANSAERO project [1] to estimate side wind effects on a typical high-speed train Air flow around a detailed geometry of the German InterRegio train was simulated by solving numerically the Reynolds-averaged Navier-Stokes equations, combined with the k — e turbulence model in three dimensions Finite volume discretization was used to obtain the flow field around the train under different wind conditions and Reynolds numbers up to 1063 x 108 The investigation was extended beyond the study of the flow characteristics to examine new concepts for protecting the trains from side wind For this purpose, numerical simulation of the flow around a train travelling on an embankment behind a solid noise barrier was carried out Detailed analysis of the results showed that noise barriers are effective means in reducing side wind induced forces and moments

Franz Durst

Papers

Design and construction of aeration systems for optimum operation of large wastewater treatment plants

Method and device for the combustion of liquid fuel

Measurement of bubbles by Phase Doppler technique and trajectory ambiguity

Developments in Laser Techniques and Fluid Mechanics

Numerical Computation of 3—D Turbulent Flow Around High—Speed Trains Under Side Wind Conditions