Computation of unsteady flow fields and trajectories of moving bodies

Fluid body interaction is a phenomenon that is simple to observe, but very complicated to understand. It affects many aspects in our daily lives; waves pushing against a buoy or flags fluttering in the wind. This study seeks to understand fluid-body interaction by looking at how flow structures are created over a body placed in a uniform flow, obtain useful flow characteristics and then provide a simple model of how fluid-body interaction takes place. Firstly, steady and unsteady computations of uniform flow over a rotating circular cylinder at various Reynolds numbers and rotation rates are carried out. This is followed by an unsteady computation of the flow structures over a single non-rotating cylinder flanked by two smaller rotating cylinders placed in a uniform flow. Finally, a simple constrained two-dimensional computation of a rigid body in free-fall is carried out to observe the trajectory and flow characteristics of the body. It is seen that the flow structures obtained from both the rotating cylinder cases are similar to those obtained computationally, as well as experimentally. It is also seen that in the case of the falling body problem, the moment of inertia of the body as well as the flow structures created as the body undergoes free-fall play an important part in the flow characteristics and behavior. Fluid body interaction has potential applications in flapping and adaptive wing studies, and therefore, it is suggested that further studies investigating the effects of existing flow structures on simple body flow characteristics, as well as the effects of interaction between uniform and rotating flow structures be carried out.Bachelor of Engineering (Aerospace Engineering

Predictive modeling for composites properties based on reinforcing fibre architecture

Use of structurally reinforced composites is widespread in many industries and applications due to their high strength-to-weight ratio. For textile fiber architectures, their entwined nature ensures that multi-directional integrity is maintained without being affected much by climate and other wear-and-tear. Different types of fiber reinforcement architectures impart different properties to the corresponding composites. This study seeks to compare the mechanical properties of differently structured performs – namely, unidirectional, woven and braided textiles. Novel expressions for the transverse Young’s modulus and Poisson’s ratio of unidirectional fibers were derived to provide improvements over the contemporary computational and classical models. These new expressions make use of shear effects at the yarn-matrix interface and are adapted for non-circular yarns as well. Consequently, mechanical property predictors for woven and braided textile composites are created. Geometric and mechanical stiffness models in MATLAB® using Classical Lamination Theory (CLT) are developed. These models make use of contemporary as well as the new-improved yarn formulations. As envisaged, improvements over the existing textile modeling work are observed. A general modeling methodology that can be used for implementing CLT for predicting properties of other textiles (such as knitted) is also established.MASTER OF ENGINEERING (MAE