Inertial migration of a sphere in plane Couette flow

We study the inertial migration of a torque-free neutrally buoyant sphere in wall-bounded plane Couette flow over a wide range of channel Reynolds numbers, $Re_c$, in the limit of small particle Reynolds number\,($Re_p\ll1$) and confinement ratio\,($\lambda\ll1$). Here, $Re_c = V_\text{wall}H/\nu$ where $H$ denotes the separation between the channel walls, $V_\text{wall}$ denotes the speed of the moving wall, and $\nu$ is the kinematic viscosity of the Newtonian suspending fluid; $\lambda = a/H$, $a$ being the sphere radius, with $Re_p=\lambda^2 Re_c$. The channel centerline is found to be the only (stable)\,equilibrium below a critical $Re_c\,(\approx 148)$, consistent with the predictions of earlier small-$Re_c$ analyses. A supercritical pitchfork bifurcation at the critical $Re_c$ creates a pair of stable off-center equilibria, symmetrically located with respect to the centerline, with the original centerline equilibrium simultaneously becoming unstable. The new equilibria migrate wallward with increasing $Re_c$. In contrast to the inference based on recent computations, the aforementioned bifurcation occurs for arbitrarily small $Re_p$ provided $\lambda$ is sufficiently small. An analogous bifurcation occurs in the two-dimensional scenario, that is, for a circular cylinder suspended freely in plane Couette flow, with the critical $Re_c$ being approximately $110$

AERODYNAMIC ANALYSIS OF MORPHING WING

This thesis presents a modelling and design exploration study of a novel twisting wing whose motion is enabled by a tensegrity mechanism. First, the aerodynamic characteristics of the twisting wing, which does not require control surfaces to modulate its shape, are compared with those of a conventional wing having a control surface. It is shown via computational fluid dynamics analyses that the twisting wing displays higher lift-to-drag ratio than the conventional wing and hence the twisting wing is more aerodynamically efficient. In addition, due to the reduction of discontinuous rudder surfaces, morphing wings can further improve the stealth performance. A finite element model with geometrical nonlinear effects is then proposed to correct the errors of the linear analysis and verify the effectiveness of the optimization method. This design is shown to be able to reduce the overall weight of the structure and achieve control of the macro mechanical performance of the wing. The work provides a general optimization design method for similar modular structures, allowing independent programmable adjustment of the parameters of each single structural cell

Binary metal oxide and polymer based liquid repellent self-cleaning surfaces

Ph.DDOCTOR OF PHILOSOPH

A Novel Intermetallic Nickel Aluminide (Ni3Al) as an Alternative Automotive Body Material

Investigation on Intermetallic Nickel Aluminides (Ni3Al) was carried to determine the suitability of this material to replace the existing automotive body. The purpose is to produce vehicles which are lighter, more fuel efficient and cause less pollution. One key technical design strategy for improving vehicles efficiency is the light weighting. Attractive properties of Ni3Al including low density (~ 6g/cm3) resulting lightweight, high oxidation and corrosion resistance, combined with their ability to retain strength and stiffness at elevated temperatures lead to its selection as a candidate alternative material. The prime focus will be on to obtain the mechanical properties such as hardness which was tested using Vickers Micro hardness Tester. XRD was used to determine the crystal structure of the designed alloy. Microstructural properties of these alloys were examined using optical microscopy and Scanning Electron Microscopy (SEM). SEM equipped with EDX used to do compositional analysis. Heat treatment (annealing) and Tafel extrapolation tests were carried out for thermal and corrosion properties of the intermetallic nickel aluminides respectively

Comparison of radiological and functional outcome in patients with fracture shaft of humerus treated with interlocking nailing and with plate osteosynthesis: A Prospective study

INTRODUCTION: Fracture of the shaft of the humerus represents 3 to 5 % of all fractures. Current research in this area focuses on defining the incidence and health care resources needed to treat these fractures, refining the indications for surgical intervention, decreasing the surgical failure rate through new implants and techniques, and minimizing the duration and magnitude of disability post injury. The successful treatment does not end with bony union but the current emphasis is on a holistic approach of patient care. The treatment of the humeral shaft fractures demands a knowledge of anatomy, surgical indications, techniques and implants, and patient function and expectations. The goal of operative treatment of humeral shaft fractures is to re-establish length, alignment and rotation with stable fixation that allows early motion and ideally early weight bearing on the fractured extremity. The Plate osteosynthesis remains the gold standard of fixation of humeral shaft fractures against which other methods can be compared. Although it has high union rate, it involves extensive dissection and soft tissue stripping, chance of injury to radial nerve and infection is present. The Intramedullary interlocking nailing has the advantage of minimal surgical exposure and soft tissue dissection, with stable fixation and rotational control. It can be done antegrade or retrograde manner. AIM: The aim of this study is to compare the Radiological and Functional outcome in patients with fracture shaft of the humerus treated with Dynamic Compression plating and those treated with Intramedullary Interlocking nailing. MATERIALS AND METHODS: This is a prospective comparative study of 22 patients with humeral shaft fractures treated with Intramedullary interlocking nailing and Plate osteosynthesis done in the Department of Orthopaedics,Government Kilpauk Medical College Hospital from April 2009 to May 2010. Inclusion Criteria - • Acute fractures of humeral shaft, • Patients aged above 18 years, • Fractures 2cm below surgical neck and 3 cm above olecranon fossa, • Multiple injuries, • Neurovascular involvement, • Osteoporotic bone, • Angulation more than 15 degrees, • Non compliance in conservative treatment. Exclusion Criteria - • Open physis, • Age less than 18 years, • Fractures involving proximal 2 cms and distal 3 cms of the humeral Diaphysis. RESULTS: Majority of the patients taken for the study both in the Interlocking nailing group and in the Plating group are in the age group of 21 to 40 years (60 – 70%). Majority of the patients in the study who sustained fracture shaft of humerus are males both in the interlocking nailing and in the plating group. The mode of injury in most of the cases in both the groups are due to Road Traffic Accidents (70% in IL nailing group and 67% in Plating group).The remaining are due to fall and due to assault. 50 – 60 % of the patients in the study have involvement of the dominant side in both groups. The most common type of fracture in our study in both the groups according to AO classification is Type A. The next type in frequency is Type B. CONCLUSION: In our study, there is no significant difference in the period of union of fractures after both the methods . The chance of infection is more in the Plating group than in patients treated with Closed reduction and Interlocking Nailing patients. The Restriction of shoulder movements are seen in patients in the Nailing group possible due to Prominent nail tip at the entry site and also due to violation of the Rotator Cuff . Non union can occur due to distraction of the fracture site while Nailing