A numerical study on combined baffles quick-separation device

The transfer of particles in laminar and turbulent flows has many applications in combustion systems, biological, environmental, nanotechnology. In the present study, a Combined Baffles Quick-Separation Device (CBQSD) is simulated numerically using the Eulerian-Lagrangian method and different turbulence models of RNG k-ε, k-ω, and RSM for 1–140 μm particles. A two-way coupling technique is employed to solve the particles’ flow. The effect of inlet flow velocity, the diameter of the splitter plane, and solid particles’ flow rate on the separation efficiency of the device is examined. The results demonstrate that the RSM turbulence model provides more appropriate results compared to RNG k-ε and k-ω models. Four thousand two hundred particles with the size distribution of 1–140 µm enter the device and 3820 particles are trapped and 380 particles leave the device. The efficiency for particles with a diameter greater than 28 µm is 100%. The complete separation of 22–28 μm particles occurs for flow rates of 10–23.5 g/s, respectively. The results reveal that the separation efficiency increases by increasing the inlet velocity, the device diameter, and the diameter of the particles.

The sedimentary environment

This chapter introduces the roles of sediment properties and hydrodynamic conditions in influencing soft-sediment communities. It identifies environmental factors that are commonly used to characterise soft-sediment habitats and used to tease out the role of habitat variation from other factors that influence populations and communities. The differences between cohesive and non-cohesive sediments that profoundly influence ecosystem functions are described. Hydrodynamics particularly at the sediment–water interface are introduced as a critical factor affecting many ecosystem processes. The chapter introduces the differences in laminar and turbulent flows. Coastal soft sediments in particular are places of high organic matter remineralisation and thus critical for the recycling of primary nutrients and primary production, particularly by microphytobenthos. These factors underpin the important role of marine sediments in biogeochemistry and earth system processes.

Effect of Soccer Ball Panels on Aerodynamic Characteristics and Flow in Drag Crisis

The panel patterns of soccer balls that change with each World Cup have a significant impact on the balls’ aerodynamic and flight characteristics. In this study, the aerodynamic forces of eleven types of soccer ball with different panel patterns were measured in a wind tunnel experiment. We characterized the panel shapes of soccer balls by the length, cross-sectional area, and the panel grooves’ volume. The results confirmed that the drag and drag crisis characteristics are dependent on the groove length and volumes. Flow separation points were visualized by an oil film experiment and particle image velocimetry (PIV) measurement to understand the drag crisis of the soccer balls. The results showed that the panel shape of the ball significantly changes the position of the separation point near the critical region, where the drags crisis occurs. In the critical region, laminar and turbulent flows coexist on the ball. On the other hand, the effect of panel shape on the separation point position is small in subcritical and supercritical states.

Geometrically Calibrated Network Models for Progressive Cavity Pump Design

Summary Linear network models are promisingly simple progressive cavity pump design tools. Current linear network models are difficult to use in the design process because they require calibration against experimental data or computationally intensive simulation. In this paper we present new approaches for implementing linear network progressive cavity pump models and provide new methods to accurately and quickly estimate the values of each resistor in the model from pump geometry for both laminar and turbulent flows. This paper also argues that sealing-line flow transitions from laminar to turbulent at orders of magnitude smaller Reynolds numbers than described in the literature thus far. We propose a new hypothesis for the point of transition to turbulent performance.

Análisis CFD de flujos turbulentos desplazados por bombas centrífugas con bajo número de Reynolds

Numerical methodologies have presented an inexpensive solution of laminar and turbulent flows capable of predicting a wide range of mechanical devices in science and engineering. Computational tools have been employed in recent years to analyze the conservation equations behavior used to describe the interaction between turbulent and laminar flows used to transfer the energy needed to perform a complex mechanical system. Due to the above, this paper purpose the application of the numerical method linked to mathematical algorithms capable of generating an approximated solution of the partial differential equations system which determines pressure, and velocity values related to the centrifugal pump performance under low Re conditions in a virtual environment through OpenFOAM software, and Salome 8.3.0. An independence mesh analysis was computed to study the computational effort required to establish an approximated turbulence phenomena description performed by the centrifugal pump into the virtual environment supported by MRFSimpleFoam solver.