Scale turbulence, summary

This chapter presents the experimental modeling of flares as turbulent diffusion flames in crossflow. We have reviewed the parameters that affect the flare performance in the field. Experimenfal facilities and insfru-mentation employed for model sfudies are presented. A summary of existing data on flame appearance, geometry, radiation, and stability has been included. Data on inflame temperature, velocity, and species concentration fields have also been discussed. Field fesf dafa are to be used in conjunction with laboratory model data to validate the results and derive scaling relations. 

The basic issues of interest with respect to the K theory are (1) under what conditions on the source configuration and the turbulent field can this theory be applied and (2) to what extent can the eddy diffusivities be specified in an a priori manner from measured properties of the turbulence. In summary, the spatial and temporal scales of the turbulence should be small in comparison with the corresponding scales of the concentration... 

Due to the importance of turbulence in spray systems, this topic is treated in some detail. It includes a summary of time averaging and spatial filtering, followed by a description of RANS and LES turbulence modeling. The RANS model that is presented is the k—s turbulence model, and the LES SGS models that are outlined include the Smagorinsky model and the one-equation subgrid scale (SGS) model. 

In summary, even though the characteristic length scales of turbulent flows in microchannels are several orders of magnitudes smaller than their counterparts in macroscale pipes and channels, experimental evidence suggests the flows are statistically and structurally similar. As such, long established correlations for pressure drop in pipes and channels and computational tools available for the study of turbulent pipe and chaimel flows should be equally applicable to turbulent microchannel flows. 

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