Ema Muk-Pavic

Bio: Ema Muk-Pavic is an academic researcher from University College London. The author has contributed to research in topics: Turbulence & Boundary layer. The author has an hindex of 4, co-authored 9 publications receiving 26 citations.

Numerical Analysis of a Leading Edge Tubercle Hydrofoil in Turbulent Regime

Abstract: This paper presents a numerical performance evaluation of the leading edge tubercles hydrofoil with particular focus on fully turbulent flow regime. Efforts were focused on the setting up of an appropriate numerical approach required for an in-depth analysis of this phenomenon, being able to predict the main flow features and the hydrodynamic performance of the foil when operating at high Reynolds numbers. The numerical analysis was conducted using an Improved Delayed Detached Eddy Simulation (IDDES) for Reynolds numbers corresponding to transitional and fully turbulent flow regimes at different angles of attack for pre-stall and post stall regimes. The results show that tubercles operating in turbulent flow improve the hydrodynamic performance of the foil when compared to a transitional flow regime. Flow separation was identified behind the tubercle troughs, but was significantly reduced when operating in a turbulent regime and for which we have identified the main flow mechanisms. This finding confirms that tubercle effect identified in transitional regime is not lost in a turbulent flow. Furthermore, when the hydrofoil operates in turbulent flow regime, the transition to a turbulent regime takes place further upstream. This phenomenon suppresses a formation of a laminar separation bubble and therefore the hydrofoil exhibits a superior hydrodynamic performance when compared to the same foil in transitional regime. The analysis approach presented here proved to be capable to accurately assess flow characteristics needed to determine the flow changes required in order to match with appropriate tubercled energy saving device design resulting in favourable fow changes.

Achieving a High Accuracy Numerical Simulations of the Flow Around a Full Scale Ship

Abstract: The hydrodynamic performance of ships may be improved by the retrofit of Energy Saving Devices (ESDs). These devices are typically seen in the aft part of the ship hull and act by lowering the ship resistance, conditioning the fluid in front of the propeller and/or recovering energy from the rotational swirl of the fluid leaving the propeller. In the case of a retrofit of an existing ship no straight forward solution exists. In order to find a beneficial design that will improve hydrodynamic performance, a successful and accurate initial assessment of the flow around a hull is of the most importance. Once the flow around the hull is scrutinized in detail, and required flow changes are determined, a ship designer can progress with designing an Energy Saving Device specifically tailored to have a desired effect. This paper presents a high quality numerical evaluation of the flow around a ship hull in the full scale using a sophisticated DES model that was successfully validated against the sea trials. The findings from the numerical analysis will identify the potential improvements in the hydrodynamic performance of the ship that could be achieved by ESD.

A multi-objective optimization model for urban planning: The case of a very large floating structure

Abstract: This paper develops an optimization model for planning an artificial island composed of Very Large Floating Structures (VLFSs). The optimization model addresses the geometric shape of the island (the array of floating platforms), the land-use layout, and the transportation network. The model developed in this paper considers the specific properties related to an artificial island made of multiple floating modules. The model is formulated as a bi-level optimization problem. In the upper level problem, the decision-maker is required to decide the land-use layout and the road network structure. The user behavior pattern is obtained by solving the lower level problem, which is dependent on the decisions taken at the upper level. Given the complexity of the problem, the paper develops modifications to the genetic algorithm to find the Pareto front in a reasonable amount of time. A test case illustrates the feasibility of the proposed planning method. The transportation model execution is the most time-consuming task, which highlights the need to prune irrelevant scenarios. The Pareto front shows a substitution pattern between different land-use configurations, in accordance with the different objective functions.