An isothermal and non-isothermal numerical study of effusion cooling flow and heat transfer is conducted using a Reynolds-averaged Navier–Stokes (RANS) approach. A Reynolds stress transport (RST) turbulence model is used to predict the flow field of a staggered array of 12 rows of effusion holes, each hole inclined at 30° to the flat plate. The Reynolds number based on the hole diameter and jet exit velocity is 3800. The blowing ratio in both studies is 5. A conjugate heat transfer approach is adopted in the non-isothermal simulation. For the isothermal case, the RST model is shown to be capable of predicting the injection, penetration, downstream decay and lateral mixing of the effusion jets reasonably well. In addition, the numerical model captures the existence of two counter-rotating vortices emanating from each hole, which causes the entrainment of combustor flow towards the surface of the plate at the leading edge and downstream, influences the mixing of accumulated coolant flow, providing a more uniform surface temperature across the plate. The presence and characteristics of these vortices are in good agreement with previously published research. In the non-isothermal case, the laterally averaged cooling effectiveness across the plate is under-predicted but the trend conforms to that exhibited during experimentation.

Contrary to military or essential government buildings, most bridges are designed without any consideration for blast resistance. Fiber-reinforced polymers (FRPs) can provide an effective means for strengthening of critical bridges against such loading. This study has focused on the effectiveness of FRP retrofitting in the dynamic response of reinforced concrete bridge columns under blast loading. Using a simplified equivalent I-section with a virtual material lumped at the two flanges; a lightly meshed uniaxial finite element model was developed and successfully validated against previous studies. The proposed model was then used for a thorough parametric study on the blast resistance of bridge substructures in the form of a single-column, two-column pier frame, and an entire bridge. The study showed the benefits of strengthening with composites against blast loading. The FRP tensile strength and diameter-to-thickness ratio, steel reinforcement ratio, and column length and damping ratio significantly affect the blast resistance of an FRP-retrofitted bridge. Finally, based on the parametric study results, predictive equations with multiple linear regression and high order terms were developed statistically for the FRP retrofit design of single columns against blast loading.

Particle size reduction of dry granular material by mechanical means, also known as milling or comminution, is undoubtedly a very important unit operation in pharmaceutical, agricultural, food, mineral and paper industries. As comminution is a stochastic and a nonlinear process, an attempt was made to understand this complicated process by conducting parametric studies experimentally and computationally using discrete element method (DEM). Greater size reduction was observed at higher rotational speed of the hammer owing to the greater centrifugal force experienced by the particles. Increase in impeller wall tolerance resulted in rolling mode regime of powder bed, which was found to be significant at low impeller speeds. A numerical model based on DEM was used to simulate a hammer mill and study the breakage and kinematics of the particle motion within the hammer mill. In the simulations, increase in hammer tip speed causes higher frequency of impact of particles per unit time and higher specific energy of impact resulting in generation of much finer end product. A limit can be conceived during the breakage event. This is because as size reduction occurs, the breakage rates can fall for very fine particles as crack propagation ceases. This is because as size decreases the probability of finding a flaw also decreases. Simulations also showed a higher milling rate for big hammers as larger hammers decrease the tolerance between the milling chamber and rotating impeller. To study the effect of material properties, the energy of fragmentation was estimated and it was found to increase as the material became more cohesive.

Hydrodynamic slug flow is the commonest flow regime observed in high viscosity liquid–gas horizontal pipelines over a wide range of different flow conditions. Hydrodynamic slugging tends to generate large vibrations that may impose structural instability or even damage oil production pipelines. For that reason, there is a need to investigate high viscosity slug flow regime to understand its complex characteristics. This is pertinent when considering that existing slug flow models used in the petroleum industry to design production pipelines are not suitable for predicting the behaviour of high viscosity oil–gas flow. In this study, the effects of liquid viscosity and flow variables on slug flow regime were investigated experimentally through the analysis of two key parameters—slug frequency and slug body liquid holdup, both measured with a gamma densitometer. Comparison of the measured slug parameters to existing correlations revealed that slug body liquid holdup correlations were in close agreement with high viscosity experimental data. However, none of the existing slug frequency correlations used was able to produce accurate predictions. A new empirical correlation for slug frequency was proposed. Compared with existing correlations, the newly proposed correlation performed much better in predict- ing slug frequency of high viscosity liquid–gas flows.

This paper presents a computational and experimental study of a valveless pump driven by a noble piezoelectric composite actuator consisting of a bimorph piezoelectric plate and a metal cap. The superiority of deformation performance of the proposed composite actuator was demonstrated computationally through finite element simulation and was then verified experimentally by deflection measurements of a disc-shaped prototype under an alternating electric field. The proposed composite actuator was applied to a valveless pump in a Y-shaped fluid channel. The pump’s performance was estimated using a piezoelectric-fluid interaction finite element simulation. The effect of the fluid channel configuration was investigated, and the liquid feed volume is discussed and compared with that of conventional actuators.

A practical approach is proposed and used to investigate the electromagnetic (EM) signature of bare- faced terrain using 3D computer electromagnetic models (CEM). Six barefaced terrain types with different electrical, physical and chemical properties were investigated. They comprise homogeneous and heterogeneous terrain. The approach developed CEMs in software using reflectance spectroscopy and dielectric permittivity data. EM signature models of the barefaced terrain are based on finite inte- gration technique (FIT) solvers. The developed technique and models are valid for diverse materials under test including unconventional petroleum resources like shale rock and oil sands. The remote sensing of terrain from airborne or satellite synthetic aperture radar requires a prior determination of the EM signature for accurate classification. The implementation of our new method combined empirical measurements and FIT in three steps. Geochemical properties determined using reflectance spectros- copy in the mid-infrared region (2.5–25 µm) identified the presence of bitumen, clay and moisture in Nigerian oil sands while reststrahlen effects were observed in beach sand compared with gravel and pebble. Also new information on both real, e′r and imaginary, e′r permittivity of terrain was experimentally obtained for frequency varying from 1 to 11 GHz. After post-processing, the results differed from expectation of complex refractive index method for petrophysics although adequate Kramers–Krönig correlation between measured real, e′r and imaginary, e′r permittivity data was exhibited. Our approach uses the results to improve the CEMs for superior EM signature determination. An application of our new technique to land degradation monitoring using radar is also presented.