a b s t r a c tThis paper presents an improved flow pattern map for predicting the heat transfer coefficients during condensation of R-134a inside a smooth horizontal tube. Experimental tests were conducted over the low-mass flux range of 75-300 kg/m 2 s, at a nominal saturation temperature of 40°C, and with the test section vapour qualities ranging from 0.76 down to 0.03. This represents points within the annular, intermittent and stratified flow regimes. The results were used to modify the Thome-El Hajal flow pattern map to include a transition region between the stratified-wavy and annular or intermittent flow regimes. The revised flow pattern-based heat transfer correlation predicted the experimental data to a mean deviation of less than 6%.
This paper details the evaluation and enhancement of the vertex-centred finite volume method for the purpose of modelling linear elastic structures undergoing bending. A matrix-free edge-based finite volume procedure is discussed and compared with the traditional isoparametric finite element method via application to a number of test-cases. It is demonstrated that the standard finite volume approach exhibits similar disadvantages to the linear Q4 finite element formulation when modelling bending. An enhanced finite volume approach is proposed to circumvent this and a rigorous error analysis conducted. It is demonstrated that the developed finite volume method is superior to both standard finite volume and Q4 finite element methods, and provides a practical alternative to the analysis of bending-dominated solid mechanics problems.
A fully-coupled partitioned finite volume-finite volume and hybrid finite volume-finite element fluid-structure interaction scheme is presented. The fluid domain is modelled as a viscous incompressible isothermal region governed by the Navier-Stokes equations and discretised using an edge-based hybrid-unstructured vertex-centred finite volume methodology. The structure, consisting of a homogeneous isotropic elastic solid undergoing large, non-linear deformations, is discretised using either an elemental/nodalstrain finite volume approach or isoparametric Q8 finite elements and is solved using a matrix-free dual-timestepping approach. Coupling is on the solver sub-iteration level leading to a tighter coupling than if the subdomains are converged separately. The solver is parallelised for distributed-memory systems using METIS for domaindecomposition and MPI for inter-domain communication. The developed technology is evaluated by application to benchmark problems for strongly-coupled fluid-structure interaction systems. It is demonstrated that the scheme effects full coupling between the fluid and solid domains, whilst furnishing accurate solutions.
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