Poojitha D. Yapa
Professor
130 Rowley Laboratories
Clarkson University
PO Box 5710
Potsdam, NY 13699-5710
Phone: 315-268-7980
FAX: 315-268-7985
E-mail: pdy@clarkson.edu
Research Site
Education
Ph.D. - Clarkson University, Potsdam, NY, 1983
M.Eng. - Asian Institute of Technology, Bangkok, Thailand, 1979
B.Sc. Eng. (Honors) - University of Moratuwa, Sri Lanka, 1976
Teaching
CE 574 Hydrodynamic Dispersion
CE 572 Shallow Water Hydrodynamics
CE 330 Water Resources Engineering I
ES 330 Fluid Mechanics
ES 220 Statics
CE 301 Engineering Measurements
Research Interests
- Modeling of deep water oil and gas jets/plumes
- Modeling gas hydrates plumes emanating from underwater releases
- Modeling of fate of oil spills and related oil spill processes
- Oil transport and spread in ice covered waters
- Impact on the ecosystem due to oil spills
- Sediment plumes and their effect on the ecosystem
- Modeling deepwater sediment plumes from mining
- Oil shoreline interaction
- Web based model systems
Vistiting Appointments
January to June 2007 Erskine Fellow, Department of Civil Engineering, University of Canterbury, Christchurch, New Zealand,
June-July 2004 Visiting Researcher, School of Marine Science, Tokai University, Shizuoka, Japan, on leave from Clarkson University
1999 to 2000 Visiting Professor / Gledden Senior Visiting Fellow, Centre for Water Research, The University of Western Australia, Perth, Australia,
Sep. 1992 to Aug. 1993 Invited Research Fellow, Department of Civil Engineering, Science University of Tokyo, Japan.
June to Aug. 1992 Visiting Researcher, Environmental Assessment Dept., National Inst. for Resources and Environment, Tsukuba, Japan.
CDOG (Clarkson Deepwater Oil and Gas) Blowout Model
CDOG simulates the behavior of oil and gas accidentally released from deep water. This is a three-dimensional model. In deepwater, the ultra-high pressure and cold temperature causes phase changes in gasses. These effects combined with deepwater currents in some regions presents extraordinary challenges to modeling jets/plumes from deepwater oil and gas blowouts.
CDOG model incorporated the phase changes of gas, associated changes in thermodynamics and its impact on the hydrodynamics of the jet/plume. Hydrate formation, hydrate decomposition, gas dissolution, non-ideal behavior of the gas, and the jet/plume hyrodynamics and thermodynamics.
CDOG can take 3-D currents, salinity, water temperature (hence water density) that varies both spatially and temporally. CDOG model has been used to numerically simulate the large scale and unique field experiments conducted in Norway at a cost of US $2.5 million. The field experiments consisted of two oil and methane gas releases and one methane gas only release from a deepwater location (844 m water depth). The comparisons between the simulations and the observations are good. CDOG model has also been used to simulate various anticipated deepwater blowout scenarios. It can be used during real emergencies or for contingency planning.
SPEED (Sediment Plume and Environmental Effect from Deep-sea Mining)
SPEED is a three-dimensional numerical model that simulates the sediment plumes released upwards (due to momentum of the mining tool) or downwards at a higher up release station. Both near-field dynamics phase and far-field passive advection-diffusion phase are considered. Plume dynamics is based on a Lagrangian integral technique. Far field simulations use the Lagrangian discrete parcel method. The model can simulate both fixed source and moving source release. The effects of different particle sizes, sediment concentration and flocculation on settling velocities are considered.
A multiple grid scheme is applied when the mining domain is very large or mining time is very long. In addition to the behavior of sediment transport, the model simulates the chemical distribution due to sediment transport, estimates the mortalities of benthos due to deposited sediment and assesses the effects on photosynthesis due to sediment plume. The model can handle heavy metals, organic chemicals, nutrients and minerals. The partitions of chemicals between water and sediment are considered. The mortality of benthos is calculated based on LC50 and first order kill rate.
COSM (Clarkson Oil Spill Model)
COSM is a two-dimensional oil spill model that has been applied to ocean environment. It can be applied to lakes. It is an easy to use model. The model is developed based on efficient numerical algorithms. Most recently COSM was applied to Guanabara Bay in Brazil.
WINROSS - An Integrated Oil and Chemical Spill Model For the St. Lawrence River Oil Spill Response The current version of the Clarkson River Oil Spill Simulation Model - WinROSS is designed to run under windows. It is completely interactive and GUI Menu based. Data input, running the models (flow model an oil spill model), and output visualization all can be done from the GUI. The model is two-dimensional and has two-layers (surface and water column). It uses the Lagrangion Parcels Method. The model is an integrated part of the St. Lawrence River Oil Spill Preparedness Plan and is used by the St. Lawrence Seaway Development Corporation.
A 2-Dimensional 2-Layer Model was developed specifically for River Oil Spill Simulation (ROSS). Early versions of ROSS2 were applied St. Clair, St. Mary's and Detroit Rivers. Lake and River combined version LROSS was applied to Lake St. Clair/Detroit river system. A modified version ROSS2 of was applied to Ohio-Monangahela-Allegheny river system. This river system is complex in many ways: the total river system length is over 300 miles; the rivers have many meanders; the system has many navigation Locks that make the simulation difficult.
A modified version of ROSS2 was applied to St. Lawrence River. This model is part of the St. Lawrence River Oil Spill Preparation Plan. ROSS3 was developed specifically to improve simulations in rivers and handle branching rivers. ROSS 3 was applied to St. Clair river/tidal flat system. The model also simulates oil spill under conditions changing shoreline locations. ROSS 2 and ROSS3 were also available in Integrated versions where the users could enter data through interactive menus and visualize the results through the same interface.
With the advent of the Windows era ROSS2 was modified for and a GUI was added. This version is named WinROSS and has been applied to St. Lawrence River.
Selected Publications
Xie, H., Yapa, P. D., and Nakata, K. (2007) “Modeling Emulsification after an Oil Spill in the Sea,” Journal of Marine Systems, Elsevier, (accepted for publication).
Chen, F.H. and Yapa, P. D., (2007). “Estimating the Oil Droplet Size Distributions in Deepwater Oil Spills,” Journal of Hydraulic Engineering, ASCE, (scheduled for publication, February 2007)
Xie, H. and Yapa, P. D. (2006) “Developing A Web-Based System For Large Scale Environmental Hydraulics Problems With An Application To Oil Spill Modeling", Journal of Computing in Civil Engineering, ASCE, May, Vol. 20 (3), 197-209.
P.D. Yapa, and F.H. Chen, "Behavior of Oil and Gas from Deepwater Blowouts," Journal of Hydraulic Engineering, ASCE, June, 540-553,(2004).
F.H Chen, P.D. Yapa and K. Nakata, "Simulating the Biological Effect of Oil Spills in Tokyo Bay by Using A Coupled Oil Spill - Toxicity Model," Journal of Advanced Marine Science Technology, AMTEC, Tokyo, Japan, 9(2), 131-155, (2004).
H. Xie and P.D. Yapa, "Simulating the Behavior and the Environmental Effect of Sediment Plumes from Deepwater Mining," Journal of Advanced Marine Science Technology, AMTEC, Tokyo, Japan, 9(1), 7-35, (2003).
F.H. Chen and P.D. Yapa, "Three-Dimensional Visualization of multi-phase (oil/gas/hydrate) plumes," Journal of Environmental Modelling and Software, Elsevier, the United Kingdom, 19(2004), 751-760, (2003).
F.H. Chen and P.D. Yapa, "Modeling Gas Separation From a Bent Deepwater Oil and Gas Jet/Plume," Journal of Marine Systems, Elsevier, the Netherlands, Vol 45 (3-4), 189-203, (2004).
H.T. Shen, X. Qing, and P.D. Yapa, "Lampricide Transport in Upper St. Marys River," Journal of Great Lakes Research, 29 (Sup1), 694-705, (2003).
L. Zheng, P.D. Yapa and F.H. Chen, "A Model for Simulating Deepwater Oil and Gas Blowouts - Part I: Theory and Model Formulation" Journal of Hydraulic Research, IAHR, August, 41(4), 339-351, (2003).
F.H. Chen and P.D. Yapa, "A Model for Simulating Deepwater Oil and Gas Blowouts - Part II : Comparison of Numerical Simulations with "Deepspill" Field Experiments", Journal of Hydraulic Research, IAHR, August, 41(4), 353-365, (2003).
P.D. Yapa and H. Xie, "Modeling Underwater Oil/Gas Jets and Plumes : Comparison with Field Data," Journal of Hydraulic Engineering, ASCE, September, 855-860, (2002).
L. Zheng and P.D. Yapa, "Modeling Gas Dissolution in Deepwater Oil/Gas Spills," Journal of Marine Systems, Elsevier, the Netherlands, March, 299-309, (2002).