Browsing by Subject "turbulence model"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Multi-Resolution Simulations of Delta/Diamond Wing Aerodynamics(2014-08-12) Cooper, JacobThis dissertation investigates high angle of attack delta wing flow at multiple resolutions of turbulence closure. The work is divided into four studies. The objectives of each study are: (i) to identify the limits of RANS modeling, (ii) explore the challenges of applying the PANS model to the delta wing flow, (iii) identify the appropriate resolution required to capture specific flow features, and (iv) determine the physical differences between sharp and round leading edge separation. The outcomes from each of these studies are as follows. Steady-state RANS modeling is shown to be adequate for low and moderate angles of attack, except in regions near the point of primary vortex separation. At low Reynolds number the vortex structure on the forward portion of the wing is mostly laminar and must be fully resolved by the grid in order to capture the physics in the aft region. Also at low Reynolds numbers, it is shown that lower resolution simulations perform adequately in capturing important integral flow features such as pressure coefficient and the locations of the vortex separation and attachment lines. High resolution simulations of low Reynolds number flow do resolve more subtle flow features that do not significantly affect the aerodynamic characteristics. The principle advantages of high resolution simulations are most evident at high Reynolds numbers and high angles of attack. The relationship between scale resolution and observed flow features is established. The simulations establish the key flow feature differences between round and sharp leading edge wing at different length scales of motion. Features of interest are the intensity of the vortex structure, the levels of turbulence, surface streamline patterns, and surface pressure coefficient. Differences between the delta and diamond wing shapes are also identified.Item Performance and application of the Modular Acoustic Velocity Sensor (M.A.V.S.) current meter for laboratory measurements(Texas A&M University, 2005-02-17) Besnard, StephaneEvery type of current meter is different and has its proper characteristics. Knowing the performance of a current meter is essential in order to use it properly either for field or laboratory measurements (such as in the Offshore Technology Research Center wave basin). A study of the MAVS (Modular Acoustic Velocity Sensor) in a wave basin is a first step essential for later deployment in real studies. This thesis is based on data obtained from different series of laboratory measurements conducted in the OTRC wave basin. The objective of the first part of the study was to characterize the MAVS frequency response using benchmarks such as tow tests or wave tests. These benchmarks allowed us not only to characterize the sensor but also to eventually correct some of the measurement distortions due to flow blockage, vortex shedding, or vibrations of the mounting structure, for example. After the preliminary study was done, we focused on the potential use of the MAVS in the OTRC wave basin. Indeed, in the case of a study of a scale model in the wave basin, the stresses applied to the model have to be accurately known. In the case of current-induced loads, this includes contributions from both the mean flow and the turbulence. Thus, after correcting the values measured by the MAVS, a mapping of the current jet was executed to determine its three-dimensional structure in the wave basin. Knowing the structure of the current in the OTRC wave basin, it was then possible to define a domain in which the current can be considered uniform with a certain tolerable error. This domain of uniformity will allow us to validate the use of the OTRC wave basin to study large models such as FPSOs (Floating Production, Storage and Offloading Units).