Wave Influenced Wind and the Effect on Offshore Wind Turbine Performance

In this paper the effect of wave influenced wind on offshore wind turbines is studied numerically. The wave is seen as a dynamical roughness that influences the wind flow and hence the wind turbine performance. An actuator line representation of the NREL's 5 MW offshore baseline wind turbine is placed in a simulation domain with a moving mesh that resolves the ocean waves. These wave influenced wind turbine simulations, WIWiTS, show that the wave will influence the wind field at the turbine rotor height. Both the produced power and the tangential forces on the rotor blades will vary according to the three different cases studied: wind aligned with a swell, wind opposing the swell and wind over a surface with low roughness (no waves).publishedVersio

Multi-fluid CFD analysis in Process Engineering

An overview of modelling and simulation of flow processes in gas/particle and gas/liquid systems are presented. Particular emphasis is given to computational fluid dynamics (CFD) models that use the multi-dimensional multi-fluid techniques. Turbulence modelling strategies for gas/particle flows based on the kinetic theory for granular flows are given. Sub models for the interfacial transfer processes and chemical kinetics modelling are presented. Examples are shown for some gas/particle systems including flow and chemical reaction in risers as well as gas/liquid systems including bubble columns and stirred tanks.publishedVersio

Computer Simulation of Turbulent Reactive Gas Dynamics

A simulation procedure capable of handling transient compressible flows involving combustion is presented. The method uses the velocity components and pressure as primary flow variables. The differential equations governing the flow are discretized by integration over control volumes. The integration is performed by application of up-wind differencing in a staggered grid system. The solution procedure is an extension of the SIMPLE-algorithm accounting for compressibility effects

Engineering Fluid Dynamics

Over the last few decades, the use of computational fluid dynamics (CFD) and experimental fluid dynamics (EFD) methods has penetrated into all fields of engineering. [...

Engineering Fluid Dynamics

This book contains the successful submissions to a Special Issue of Energies on the subject area of “Engineering Fluid Dynamics”. The topic of engineering fluid dynamics includes both experimental as well as computational studies. Of special interest were submissions from the fields of mechanical, chemical, marine, safety, and energy engineering. We welcomed both original research articles as well as review articles. After one year, 22 papers were submitted and 12 were accepted for publication. The average processing time was 65.2 days. The authors had the following geographical distribution: China (four); Italy (two); Korea (one); Germany (one); UK (one); Ireland (one); Australia (one); Sweden (one); Japan (one); Spain (one); Norway (one). Papers covered topics such as heat transfer in shell and helically coiled tube heat exchangers, the multiphase modeling of sprays, flashing flows, as well as mixing in a bubbling fluidized bed. Two papers related to heating ventilation and air condition (HVAC) are included, namely evaporation and condensation in the underfloor space of detached houses and air distribution in a railway vehicle. Three papers dealt with various aspects of pumps and turbines: a performance prediction method for pumps as turbines; noise radiation in a centrifugal pump; periodic fluctuations in energy efficiency in centrifugal pumps; and study of a high-pressure external gear pump. One paper used both laser doppler velocimetry (LDV) and CFD in the study of flow behind a semi-circular step cylinder. Finally, a paper investigated the influence of the equivalence ratio (ER) and feedstock particle size on birch wood gasification

Experimental and Computational Studies of Turbulent Mass Transfer in a Mixing Channel

Experiments are carried out for passive mixing in order to obtain local mean and turbulent velocities and concentrations. The mixing takes place in a square channel with two inlets separated by a block. A combined PIV/PLIF technique is used to obtain instantaneous velocity and concentration fields. Three different flow cases are studied. The 2D numerical predictions of the mixing channel show that none of the k - ε turbulence models tested is suitable for the flow cases studied here. The turbulent Schmidt number is reduced to obtain a better agreement between the measured and predicted mean and fluctuating concentrations. The multi-peak presumed PDF mixing model is tested and comparisons with experiments are encouraging