Design and Aerodynamic Investigation of Dynamic Architecture

The effect of the spacing between adjacent building floors on the wind distribution and turbulence intensity was analysed using computational fluid dynamics in this study. Five computational models were created with floor spacing ranging from 0.8 m (benchmark) to 1.6 m. The three-dimensional Reynolds-Averaged Navier–Stokes equations along with the momentum and continuity equations were solved using the FLUENT code for obtaining the velocity and pressure field. Simulating a reference wind speed of 5.5 m/s, the findings from the study quantified that at a floor spacing of 1.6 m, the overall wind speed augmentation was 39 % which was much higher than the benchmark model (floor spacing = 0.8 m) indicating an amplification in wind speed of approximately 27 %. In addition, the results indicated a gradual reduction in turbulence kinetic energy by up to 53 % when the floor spacing was increased from 0.8 to 1.6 m. Although the concept was to integrate wind turbines into the building fabric, this study is limited to the assessment of the airflow inside the spaces of building floors which can be potentially harnessed by a vertical axis wind turbine. The findings of this work have indicated that there is a potential for integration which will lead on to future research in this area

Transient Thermal Analysis of Mixed-elastohydrodynamic Contact of High Performance Transmission in a Dry Sump Environment

Fuel efficiency is one of the main concerns in the optimisation of modern racing transmissions. The dry sump transmissions are the preferred choice for high performance racing applications. While it provides adequate lubricant for gear contacts, it minimises the system churning losses, and therefore enhances the system efficiency. An important aspect is assessing its thermal performance in removing the generated frictional heat. The generated heat in the highly loaded high shear contacts of racing transmissions should be dissipated through use of directed impinging oil jets and in an air–oil mist environment. The paper presents an integrated tribological and three-dimensional computational fluid dynamics analysis for a spur gear pair, incorporated into an overall finite element model to evaluate the quantity of generated heat and its removal rate from the rotating gear surfaces. Furthermore, the temperature distribution in the circumferential direction is predicted and used to evaluate transient temperature distribution over representative race laps. Such an approach has not hitherto been reported in literature

Modelling of vortex flow controls at high drainage flow rates

A number of vortex flow control (VFC) devices for urban drainage systems are investigated computationally at high flow rates, for which a confined vortex dominates the flow regime. A range of turbulence models, including both eddy viscosity and Reynolds stress closures, are compared with in-house experimental measurements of head loss and internal pressure measurements. Single-phase and multi-phase (free surface) calculations are also compared. Very good agreement with the experimental data was obtained when the swirl parameter of the device was below 3.14 for predictions made using the Reynolds stress closure formulations. For devices with swirl parameters above this value, the computational methodology was found to under-predict the head loss of the device. This was attributed to poor calibration of the turbulence model for swirling flow scenarios in which the pressure gradient and diffusive (turbulent) forces in the flow are comparable

Analysis of Dense Gas Effects in Compressible Turbulent Channel Flows

In this work we investigate the influence of dense gas effects on compressible wall-bounded turbulence. Turbulent flows of dense gases represent a research field of great importance for a wide range of applications in engineering. Dense gases are single-phase fluids with a molecular complexity such that the fundamental derivative of gas dynamics [1], which measures the rate of change of the sound speed in isentropic transformations, is less than one in a range of thermodynamic conditions close to the saturation curve. In such conditions, the speed of sound increases in isentropic expansions and decreases in isentropic compressions, unlike the case of perfect gases. For dense gases, the perfect gas model is no longer valid, and more complex equations of state must be used to account for their peculiar thermodynamic behavior. Moreover, in the dense gas regime, the dynamic viscosity μ and the thermal conductivity λ depend on temperature and pressure through complex relationships. Similarly, the approximation of nearly constant Prandtl number Pr= μ c p / λ is no longer valid. Numerical simulations of turbulent dense gas flows of engineering interest are based on the (Reynolds-Averaged Navier–Stokes) RANS equations, which need to be supplemented by a model for the Reynolds stress tensor and turbulent heat flux. The accuracy of RANS models for dense-gas flows has not been properly assessed up to date, due to the lack of both experimental and numerical reference data. DNS databases [2, 3] are then needed to quantify the deficiencies of existing turbulence models and to develop and calibrate improved ones. In this work we first summarize some recent direct numerical simulation (DNS) results [4] for supersonic turbulent channel flows (TCF) of PP11, a heavy fluorocarbon representative of dense gases, at various bulk Mach and Reynolds numbers. The most relevant effects are represented by non-conventional variations of the fluctuating thermodynamic quantities, compared to perfect gases and a strong decoupling between thermal and dynamic effects almost everywhere in the flow, except in the immediate vicinity of the solid wall. Preliminary considerations about the validity of some currently-used models for the turbulent stresses and heat flux are carried out based on a priori comparisons between the exact terms computed from the DNS and their modeled counterparts

Understanding pharmacokinetics using realistic computational models of fluid dynamics: biosimulation of drug distribution within the CSF space for intrathecal drugs

We introduce how biophysical modeling in pharmaceutical research and development, combining physiological observations at the tissue, organ and system level with selected drug physiochemical properties, may contribute to a greater and non-intuitive understanding of drug pharmacokinetics and therapeutic design. Based on rich first-principle knowledge combined with experimental data at both conception and calibration stages, and leveraging our insights on disease processes and drug pharmacology, biophysical modeling may provide a novel and unique opportunity to interactively characterize detailed drug transport, distribution, and subsequent therapeutic effects. This innovative approach is exemplified through a three-dimensional (3D) computational fluid dynamics model of the spinal canal motivated by questions arising during pharmaceutical development of one molecular therapy for spinal cord injury. The model was based on actual geometry reconstructed from magnetic resonance imaging data subsequently transformed in a parametric 3D geometry and a corresponding finite-volume representation. With dynamics controlled by transient Navier–Stokes equations, the model was implemented in a commercial multi-physics software environment established in the automotive and aerospace industries. While predictions were performed in silico, the underlying biophysical models relied on multiple sources of experimental data and knowledge from scientific literature. The results have provided insights into the primary factors that can influence the intrathecal distribution of drug after lumbar administration. This example illustrates how the approach connects the causal chain underlying drug distribution, starting with the technical aspect of drug delivery systems, through physiology-driven drug transport, then eventually linking to tissue penetration, binding, residence, and ultimately clearance. Currently supporting our drug development projects with an improved understanding of systems physiology, biophysical models are being increasingly used to characterize drug transport and distribution in human tissues where pharmacokinetic measurements are difficult or impossible to perform. Importantly, biophysical models can describe emergent properties of a system, i.e. properties not identifiable through the study of the system’s components taken in isolation

Numerical investigation of two-phase flow induced local fluctuations and interactions of flow properties through elbow.

The local interactions and fluctuations of multiphase flow properties present in upward slug/churn flow patterns through a 900 pipe bend has been investigated. Numerical modelling technique using the Volume of Fluid method (VOF) and Reynolds Averaged Naiver-Stokes equation (RANS) was used in this study. Validation of the modelling approach was carried out using the void fraction signals from the simulation and its PDF result. These signals compared well with reported experimental results for slug and churn flow patterns. Result analysis which focused on velocity and pressure fluctuations at three different cross-sectional planes of the elbow showed a reduction in the fluctuation energy (PSD) of the velocity signal at the downstream locations compared to the upstream. Similar behaviour was seen in the pressure signal. The observation was attributed to the change in multiphase flow patterns from slug to stratified/stratified wavy flow pattern after the bend. The results from this study intend to inform enhanced description of the local fluctuations of slug geometry, density and frequency for the accurate prediction of flow induced fluctuating forces due to slug-churn turbulent flows at pipe bends

Crystallisation route map

A route map for the assessment of crystallisation processes is presented. A theoretical background on solubility, meta-stable zone width, nucleation and crystal growth kinetics is presented with practical examples. The concepts of crystallisation hydrodynamics and the application of population balances and computational fluid dynamics for modelling crystallisation processes and their scaling up are also covered