On the aerodynamics of an enclosed-wheel racing car: an assessment and proposal of add-on devices for a fourth, high-performance configuration of the DrivAer model

A modern benchmark for passenger cars – DrivAer model – has provided significant contributions to aerodynamics-related topics in automotive engineering, where three categories of passenger cars have been successfully represented. However, a reference model for highperformance car configurations has not been considered appropriately yet. Technical knowledge in motorsport is also restricted due to competitiveness in performance, reputation and commercial gains. The consequence is a shortage of open-access material to be used as technical references for either motorsport community or academic research purposes. In this paper, a parametric assessment of race car aerodynamic devices are presented into four groups of studies. These are: (i) forebody strakes (dive planes), (ii) front bumper splitter, (iii) rear-end spoiler, and (iv) underbody diffuser. The simplified design of these add-ons focuses on the main parameters (such as length, position, or incidence), leading to easier manufacturing for experiments and implementation in computational studies. Consequently, a proposed model aims to address enclosed-wheel racing car categories, adapting a simplified, 35% scaled-model DrivAer Fastback shape (i.e. smooth underbody, no wheels, and with side mirrors). Experimental data were obtained at the 8ft x 6ft Cranfield Wind Tunnel using an internal balance for force and moment measurements. The aerodynamic performance of each group of add-on was assessed individually in a range of ride heights over a moving belt. All cases represent the vehicle at a zero-yaw condition, Reynolds number (car length-based) of 4.2 × 106 and Mach number equal to 0.12. The proposed high-performance configuration (DrivAer hp-F) was tested and a respective Reynolds number dependency study is also provided. In line with the open-access concept of the DrivAer model, the CAD geometry and experimental data will be made available online to the international community to support independent studies

The Voronoi inverse mapping

Given an arbitrary set T in the Euclidean space whose elements are called sites, and a particular site s, the Voronoi cell of s , denoted by VT(s)VT(s), consists of all points closer to s than to any other site. The Voronoi mapping of s , denoted by ψsψs, associates to each set T∋sT∋s the Voronoi cell VT(s)VT(s) of s w.r.t. T . These Voronoi cells are solution sets of linear inequality systems, so they are closed convex sets. In this paper we study the Voronoi inverse problem consisting in computing, for a given closed convex set F∋sF∋s, the family of sets T∋sT∋s such that ψs(T)=Fψs(T)=F. More in detail, the paper analyzes relationships between the elements of this family, ψs−1(F), and the linear representations of F , provides explicit formulas for maximal and minimal elements of ψs−1(F), and studies the closure operator that assigns, to each closed set T containing s , the largest element of ψs−1(F), where F=VT(s)F=VT(s).This work has been supported by MINECO of Spain and ERDF from EC, Grants MTM2011-29064-C03-01, MTM2011-29064-C03-02, Australian Research Council’s Discovery Projects funding scheme (project number DP140103213), Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0563), and SECTyP-UNCuyo, Argentina, Grant Res. 4540/13-R. The second author is affiliated to MOVE (Markets, Organizations and Votes in Economics)

Deterministic Lateral Displacement:Challenges and Perspectives

The advent of microfluidics in the 1990s promised a revolution in multiple industries from healthcare to chemical processing. Deterministic lateral displacement (DLD) is a continuous-flow microfluidic particle separation method discovered in 2004 that has been applied successfully and widely to the separation of blood cells, yeast, spores, bacteria, viruses, DNA, droplets, and more. Deterministic lateral displacement is conceptually simple and can deliver consistent performance over a wide range of flow rates and particle concentrations. Despite wide use and in-depth study, DLD has not yet been fully elucidated or optimized, with different approaches to the same problem yielding varying results. We endeavor here to provide up-to-date expert opinion on the state-of-art and current fundamental, practical, and commercial challenges with DLD as well as describe experimental and modeling opportunities. Because these challenges and opportunities arise from constraints on hydrodynamics, fabrication, and operation at the micro- and nanoscale, we expect this Perspective to serve as a guide for the broader micro- and nanofluidic community to identify and to address open questions in the field

Numerical simulation of fine particle separation in hindered -settling bed separators by computational fluid dynamics

The objective of the present study was to improve the understanding of multiple phase flows in hindered-settling bed separators (HSBS). A better understanding of mineral separation in HSBS and the role of structured plates was gained through studies conducted with Computational Fluid Dynamics (CFD) analysis tools. An Euler-Lagrange model from CFD technique is used for this purpose.;In an Euler-Lagrange model, two dimensional incompressible Navier-Stokes equations are solved with the implementation of a finite volume approach over staggered grids with application of Baldwin-Lomax turbulent model. The overall accuracy of the method is second-order in both space and time. The calculation of the liquid field provides the liquid velocity profile in the separator. The integration of movement equations of the particles makes it possible to track the trajectories of discrete particles in the fluid field. The integration of individual particle behavior results in a description of macroscopic behaviors of particle assembly in the fluidized-bed and makes a prediction of density separation using statistical analysis of a number of representative particles. The operating parameters including suspension density set point value, fluidizing water velocity, feed pipe water velocity, feed solid concentration, particle sizes and column geometry were investigated. The simulation has been validated against in-plant test results. Comparisons between the simulations and experiments show the capability of this multiple phase model.;An Euler-Lagrange model has also been developed which simulates the role of structured plates in the HSBS. This device utilizes corrugated plates to improve the performance of conventional hindered-settling bed separators. An investigation utilizing the model was carried out and has predicted an improved separation performance denoted by lower probable errors, lowered processing size limits, and higher throughputs at acceptable separation efficiencies. The model has also predicted that the unfavorable impact of the feed rate fluctuations is reduced significantly by the innovative addition of structured plate design. Experimental results and animation from simulation have verified that the fluid rotation exists between the structured plates to enhance the density separation. Laboratory test results indicate that improvements in separation efficiency can be achieved using the addition of structured plates. The simulation also revealed that the baffled column with structured plates can hold a broader range of suspension densities in response to the fluctuation of solid feed rate than the open column. Finally, the pulsation flows in the presence of the structured plates are simulated. It was found there exists an optimal range for frequency and amplitude of pulsation to improve separation efficiency

Numerical computations of dispersed flow and gravity stratified two-phase flow

Imperial Users onl

Design of parallel micromechanisms for knotting operation

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2009Includes bibliographical references (leaves: 61-63)Text in English; Abstract: Turkish and Englishix, 63 leavesThis thesis covers a study on the design of micromechanisms which are capable of imitating the knotting operation and their applications on carpet manufacturing.For this purpose, motion generation synthesis of a planar two degree-of-freedom serial manipulator is performed for a given path by using interpolation approximation. For a given four points, four design parameters are solved as a result of non-linear equations. Also, analysis of each stages of knotting operation is kinematically performed for the design of a cam-actuated mechanism which is designed as an alternative concept. Results of these analysis are used for the design of cam profiles those of which actuates the manipulators.After design stage of knotting micromechanisms, fully automated carpet loom design is introduced for a real-life experiment of designed mechanisms. Finally, assembly considerations of carpet loom and knotting mechanisms are given for carpet manufacturing purpose

Novel reactors for multiphase processes

Process intensification tools, such as the capillary reactor, offer several benefits to the chemical process industries due to the well-defined high specific interfacial area available for heat and mass transfer, which increases the transfer rates, and due to low inventories, they also enhance the safety of the process. This has provided motivation to investigate three such tools, namely the capillary microreactor, spinning disc and rotating tube reactors, in this study.The gas-liquid slug flow capillary microreactor intensifies reactor performance through internal circulation caused by the shear between the continuous phase/wall surface and the slug axis, which enhances the diffusivity and consequently increases the reaction rates. However, integrating the complex hydrodynamics of this reactor with its chemical kinetics is a mathematically challenging task. Therefore, in this study, a simple-to-complex approach, using a set of state-of-the-art computational fluid dynamic tools, has been used. Firstly, simulations were performed without any chemical reaction to ascertain the extent of slug flow regime. The model also clearly captured the slug flow generation mechanism which can be used to structurally optimize the angle of entry in these reactors. Finally, the hydrodynamic model was also capable of estimating the pressure drop and slug lengths. After successfully simulating the hydrodynamics of the system, a reaction model was incorporated to study the chemical reaction kinetics. The results were compared with the published experimental work and were found to be in good agreement.The spinning disc reactor utilizes the centrifugal and shear forces to generate thin liquid films characterized with intense interfering waves. This enables a very high heat transfer coefficients to be realized between the disc and liquid, as well as very high mass transfer between the liquid and the bulk gas phase. The waves formed also produce an intense local mixing with very little back mixing. This makes a spinning disc reactor an ideal contactor for multiphase processes. The focus of this study has been to elucidate the hydrodynamic behaviour of the liquid film flow over the horizontal spinning disc. Investigations were also performed to elaborate the local and overall hydrodynamic characteristics of a fully developed spinning disc reactor. Simulation results showed a continuous linear liquid film on the horizontal spinning disc and intense mixing performance in the annulus of the reactor around the disc surface. Finally, the film thickness data from the simulations were compared with the limited amount of data available for this novel process.Rotating tube reactor also uses centrifugal forces to generate the liquid film and a high degree of mixing along with an improved control over the reactant retention times. In this work we have conducted a CFD analysis to understand the hydrodynamics of this new technology for future developments