<p> Turbulent simulations are performed for model- and full-scale hydrokinetic turbine using rotating blade using solution adapted grids up to 8.8M cells. The performance characteristics at both scales, and intermediate wake predictions at model-scale are validated using experimental data, and the effect of grids, turbulence modeling, scale and stanchion on the wake recovery is evaluated. The thrust and power predictions compare within 5% of the experimental data. LES performs better than other models for the wake prediction, and the averaged error is 7% and 30% in the near and intermediate wake, respectively. The large errors in the intermediate wake are due to poor predictions of cross plane turbulent fluctuations, which results in the under prediction of the wake diffusion. The wake deficit increases due to the effect of stanchion, and increase in Re. The far-wake shows a Gaussian profile, whose width and amplitude show linear increase and decrease, respectively, with progression.</p>

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000. / Includes bibliographical references (leaves 67-68). / by Chadwyck T. Musser. / S.M.

<p> The quest for affordable energy continues to drive the need for new technology and push the limits of current practice. In the offshore arena of oil and gas exploration, massive drillships are used to penetrate reservoirs several thousand feet below the surface. The dynamic loading in the landing and casing string induced by an ocean environment is studied and a simplified model of heave in the string is developed in this thesis. An overview of the landing operations for intermediate casing strings and factors driving increasing lengths and weights of casing are presented. The available wave energy spectra for simulating the ocean wave environment and the ship&rsquo;s response to such an environment (particularly in heave) are discussed. A literature review of previous models of dynamic loading in tubulars aboard offshore vessels is presented. The development and validation of a simplified model based on two real-world case studies are also presented. Contrary to prior assumptions, for models with 10 to 50 lumped masses, an increase in the number of masses significantly decreases the dynamic loads compared to using fewer masses. A comparison of the model results to the case studies suggests that vessel heave from the ocean environment induced only a portion of the dynamic loads observed. The dynamic loads observed in the case studies are on the order of only 1% of static string weight. Operations in extreme waves are also simulated, and the maximum dynamic loads predicted are less than 5% of static string weight.</p><p>