Probabilistic modelling of wind induced air exchange in buildings

The work presented is the continuation of the research on the probabilistic modelling of air infiltration carried out by the author over many years. The approach has consisted in considering uncertainties coupled to the climatic/environmental input data to the physical models, or to the threshold criteria for a good performance. The concept of risk/reliability evaluation of building/environment system performance was proposed and exemplified for the air exchange model.  

Particle Image Velocimetry Visualization and Measurement of Airflow Over a Wall-Mounted Radiator

A common room-heating technique involves the use of a wall-mounted radiator without forced convection. The cold surrounding air passes adjacent to the warm surfaces of the radiator where it absorbs heat and gains momentum to rise along the wall surface and finally circulate in the entire room. Understanding the properties of heated airflows is important for several purposes. To understand the flow process it is important to identify where the transition from laminar to turbulent flow occurs and to quantify the turbulent fluctuations.

Large Eddy Simulation of Buoyancy-Driven Natural Ventilation – Twin-Plume Flow

This paper presents results of a Large Eddy Simulation (LES) of buoyancy-driven natural ventilation in which two unequal heat sources are used to drive the flow. The aim of this work was to assess the performance of LES in modelling turbulent thermal plumes in a naturally ventilated enclosure and to analyse their interaction with each other. The sub-grid scales of the flow have been resolved by using the Smagorinsky sub-grid scale model. It was found that LES results for the interface height agree well with the theoretical predictions of Linden and Kaye (2006).

Influence of Induction Box Ports on Near Flow Field Mixing

This paper presents the influence of air blown through an injection nozzle in a circular section induction box on the axial jet and air induction. The effect of the turbulent jet on the axial mean streamwise velocity decay, turbulence characteristics, mass entrainment and temperature distribution in the near flow field of an enclosed numerical space is investigated. Convergence of the steady state simulations is achieved by using the RNG kappa-epsilon turbulence model.

CFD Codes Efficiency Case Study: Ability to Perform Numerical Simulations in the Refrigerated Compartment of a Foodstuff Transportation Vehicle

The purpose of the present work is to describe the ability of the advanced computer packages(CFD codes) to perform numerical simulations of general refrigeration engineering problems. The case study concerns the modelling of three-dimensional turbulent airflow with thermal buoyant effects and air temperature distribution in the refrigerated compartment of a perishable foodstuff transportation vehicle.The numerical predictions obtained with three commercial codes (PHOENICS, FLUENT and CFX) and an academic one are evaluated and compared with experimental data.

About the validity of turbulence models for the computational fluid dynamics of a non-isothermal developing plane jet in aiding mixed convection regime

A comparative study between experiments and numerical simulations in the developingzone of a non-isothermal plane vertical jet is presented. Low velocity airflow, in aiding mixedconvection regime, discharging from a large rectangular nozzle in a quiescent medium at a highertemperature is considered (Re = 4220).The "Reynolds-Averaged" Navier-Stokes equations (RANS) are solved with two codes, the CFD code Fluent and the Aquilon code, including different turbulence models.

A Lagrangian model for the dispersion of solid particles, in three-dimensional flow, using a CVFEM for the prediction of the continuous phase

A Lagrangian-Eulerian model for the dispersion of solid particles in a three-dimensional, incompressible, laminar or turbulent flow is reported, tested and partly validated. Prediction of the continuous phase is done by solving an Eulerian model using a Control-Volume Finite Element Method (CVFEM). A Lagrangian model is also applied, using alternatively an analytical and a Runge-Kutta 4th order method to obtain the particle trajectories. The effect of fluid turbulence upon particle dispersion is taken into consideration through a simple stochastic approach.

Computational fluid dynamics and room air movement

This paper analyses the quality level of CFD, different aspects of the boundary conditions of supply openings are considered allong with the prediction of wall jets by different turbulence models.

Variable zone multipoint analysis in enclosure with turbulent transport properties in advanced thermal energy reduction technique

Many recently developed energy-reducing strategies with respect to heat loads in residential interiorsincluded in simulation programs possess extensive capabilities in handling these loads (gains orsinks) for each zone - spatial unit designed for maintaining moist air thermodynamics there.We have taken up procedure, which was primarily dedicated to the influence of the sensor positionsof a room model.

Numerical prediction of indoor air humidity and its effect on indoor environment

This paper describes a numerical model that takes into account the indoor air moisture and its transport by the airflow, within an enclosure. That model is a potential useful tool for correctly estimating the indoor environment in steady and homogeneous thermal conditions.