Author : Adithya Ramanathan Krishnan
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (115 download)
Book Synopsis Explicit Algebraic Subfilter Scale Modeling for DES-like Methods and Extension to Variable Density Flows by : Adithya Ramanathan Krishnan
Download or read book Explicit Algebraic Subfilter Scale Modeling for DES-like Methods and Extension to Variable Density Flows written by Adithya Ramanathan Krishnan and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this work is to improve the predictive capabilities of hybrid RANS/LES methods HRLM through the development of a subfilter scale model which considers an explicit algebraic relation for the non-isotropic turbulent subfilter stress and turbulent scalar fluxes, contributing to the improvement of the safety analysis concerning hydrogen hazards. Firstly, an Explicit Algebraic Reynolds Stress Model EARSM is developed using the direct solution method and calibrated with Menter's BSL model for incompressible flows in a RANS framework. Secondly, the EARSM model is extended to seamless HRLM specifically in the framework of Equivalent-Detached Eddy Simulation, arriving at the Explicit Algebraic Hybrid Stress Model EAHSM. The calibration of the model constant is performed on the decay of isotropic turbulence. The validation is performed against the DNS data available in the literature for the fully developed Channel flow at a moderate friction Reynolds number of 550 and flow in a square pipe at a friction Reynolds number of 600. Finally, assuming the Boussinesq approximation to be valid, the developed EARSM and the EAHSM models are extended to slightly variable density flows. Following the direct solution of the implicit algebraic relationships, the explicit algebraic model for both the Reynolds stresses and the scalar flux is obtained in a RANS framework which leads to the Explicit Algebraic Scalar Flux Model(EASFM). An effective iterative solution method is used to treat the nonlinearity of the coupled expressions for the algebraic relations. The EASFM is extended to the framework of seamless HRLM. The behaviour of the models is assessed for stably stratified flows.