A numerical method for thermal-hydraulic analysis in complex geometries (Q2751299)

An efficient computational technique was developed to studyNEWLINEthermal-hydraulics in complicated 2D or 3D geometries.NEWLINEGlobal analysis of convective heat and mass transfer in single-phase flowsNEWLINEis performed in the whole problem domain in the conjugate formulation.NEWLINENEWLINEPeculiarities of the geometry are described in the framework of the model ofNEWLINEan anisotropic porous medium, i.e., are treated viaNEWLINEdistributed volume porosity, directional surface permeabilities,NEWLINEdistributed flow resistances and heat sources/sinks.NEWLINENEWLINEConvective flows are governed by the Navier-Stokes equations for a fluid withNEWLINEvariable properties. The 2D/3D time-dependent conservation equations of mass,NEWLINEmomentum and energy with complicated source terms are solved asNEWLINEan initial/boundary value problem. Effective eddy viscosity andNEWLINEthermal conductivity can be employed to model turbulent flow regimes.NEWLINENEWLINEIn the developed mathematical model there is employed the generalized formNEWLINEof the governing equations that allows to describe thermal and hydrodynamicNEWLINEphenomena both in solids and in liquids in a unified form.NEWLINEThis fact makes possible to construct homogeneous numerical algorithmsNEWLINEfor solving conjugate convection/diffusion problems in domainsNEWLINEof complex internal structure.NEWLINENEWLINETo solve the above mathematical model, an efficient numerical algorithmNEWLINEhas been developed. Its primary peculiarities are the following: NEWLINENEWLINE-- discrete approximations are constructed using finite-difference methodsNEWLINEand the MAC-type staggered grid; NEWLINENEWLINE-- fictitious region method is used to handle irregular complex computationalNEWLINEdomains; NEWLINENEWLINE-- the Douglas-Rachford operator-splitting techniqueNEWLINEis employed to construct implicit scheme for the time-dependent equationsNEWLINEof hydrodynamics; NEWLINENEWLINE-- the fully implicit scheme is utilized for the unsteady heat equation; NEWLINENEWLINE-- second-order approximations are used for convective terms; NEWLINENEWLINE-- derived grid elliptic equations are solved at every time-levelNEWLINEusing linear iterative solvers based on preconditioned conjugate gradientsNEWLINEmethods for symmetric and non-symmetric matrices.NEWLINENEWLINENEWLINEA fast reactor with the integral equipment arrangementNEWLINEwith the sodium coolant of BN-800 type has been studiedNEWLINEnumerically using the designed computational tools.NEWLINENormal operating regimes have been considered in the 2D axisymmetricalNEWLINEformulation whereas transient processes arising at off-normal regimes wereNEWLINEinvestigated in the 3D formulation.NEWLINENEWLINEIt should be noted that the developed code can be employedNEWLINEnot only for design and safety analysis of nuclear reactorsNEWLINEbut for prediction of complex heat and flow phenomena in variousNEWLINEtechnical installations or their particular componentsNEWLINEsuch as steam generators, containment, etc.NEWLINENEWLINEFor the entire collection see [Zbl 0964.00049].