Particle tracking modeling of marine sediment pollution


Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Petroleum and Natural Gas Engineering, Turkey

Approval Date: 2015

Student: RABİA TUĞÇE ÖZDEMİR

Supervisor: İSMAİL DURGUT

Abstract:

Drilling cuttings, chemicals and drilling mud that are discharged to the sea during drilling in offshore, affect sediment habitat at sea floor. The main stressors describing the impact of discharges on marine sediment are, burial, toxicity and free oxygen depletion. In order to determine the effects of mixing of the discharged material in the sediment column, one dimensional particle tracking model that utilizes the random walk method was developed for estimating the free oxygen, natural carbon and added chemical concentrations. This method can overcome numerical diffusion and boundary effects mainly faced in numerical methods as finite difference. The general transport equation with constant bioturbation coefficient and first decay of added chemical is solved with both analytical methods and finite different method to compare the results with particle model. In addition, the stressors are modeled by the diagenetic equations which are solved with finite difference and particle methods to show the consistency of the methods. In order to overcome the oscillations in the particle model due to random behavior of particles, a Kernel smoothing method is applied. Results show that particle tracking method is a promising alternative to numerical solutions and has a stable behavior for different parameters and it is simple to apply in advection diffusion and first order decay reaction problems. On the other hand, since particle tracking method is an explicit solution, the implementation of reaction in diagenetic equations will lead to divergence between true model and particle model.