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

New numerical methods such as the lattice Boltzmann approach together with the increasing computational power can provide a detailed insight into the flow and transport processes in complex three dimensional geometries. The present paper demonstrates this approach by investigating inhomogeneities in the 3-D flow field of reacting species in a tubular fixed bed reactor of small tube-toparticle diameter ratio. For such reactors detailed 3-D simulations are of technical and economical interest as conventional modelling methods cannot correctly predict the local flow behaviour. However, these local inhomogeneities can significantly influence the reactor performance. Beside the discussion of the reaction engineering results, also the computational performance of the applied method is described.

https://link.springer.com/content/pdf/10.1007%2F978-3-642-56034-7_43.pdf

Detailed Simulation of Transport Processes in Reacting Multi-Species Flows Through Complex Geometries by Means of Lattice Boltzmann Methods

Tenth Symposium on Turbulent Shear Flows : the Pennsylvania State University, University Park, PA, U.S.A., August 14-16, 1995

There are not many key technologies left in which Europe is leading but the field of sensor and microsystem technologies is still a European domain. This is stressed in the introduction of the present paper and it is pointed out that joint efforts are needed to maintain the European lead in this field.

Development of Advanced Sensors

The invention relates to a fuel injection system, in particular a common rail injection system, in which fuel is conducted from a distributor pipe via high-pressure lines to injectors, by means of which the fuel can be injected during an injection cycle with a number of injection pulses, wherein each of the high-pressure lines is provided with at least one damping device for damping pressure pulsations. In order to simplify the production of the damping device, the damping device has a pipe, in which a core that is held at a distance via spacers so as to form an annular gap is provided.

Franz Durst

Papers

Detailed Simulation of Transport Processes in Reacting Multi-Species Flows Through Complex Geometries by Means of Lattice Boltzmann Methods

Tenth Symposium on Turbulent Shear Flows : the Pennsylvania State University, University Park, PA, U.S.A., August 14-16, 1995

Development of Advanced Sensors

Fuel injection system

Twin-jet Spray and Drop-impingement Spray Injectors for Engine Applications