HR: 1340h
AN: OS23A-1536    [Abstracts]
TI: Entrainment and transport in idealized three-dimensional gravity current simulation
AU: * Tseng, Y
EM: yhtseng@lbl.gov
AF: Computational Research Division Lawrence Berkeley National Laboratory, One Cyclotron Rd,MS:50F-1650 Bldg. 50F Rm 1622, Berkeley, CA 94720 United States
AB: A purely z-coordinate DieCAST ocean model is applied to the DOME idealized bottom density current problem that is patterned after the Denmark Strait. The numerical results show that the background viscosity plays more important role than the chosen coordinate system in the entrainment and mixing if the background viscosity is not small enough. Either higher horizontal viscosity or coarser resolution leads to slower longitudinal propagation. Reducing vertical mixing parameterization also leads to slower longitudinal propagation with larger vertical penetration. The simulation gives consistent results for the moderate and fine resolution runs. At very coarse grid, the dense water descends more slowly and is mainly dominated by diffusion. Time-averaged downstream transport and entrainment are not very sensitive to viscosity after the flow reaches its quasi-steady status. However, more realistic eddies and flow structures are found in low viscosity runs. Larger numerical dissipation is not required/recommended in z-coordinate models. The result shows good convergence of the resolved flow as expected and clarifies the influence of numerical dissipation/mixing on overflow modeling.
DE: 4211 Benthic boundary layers
DE: 4219 Continental shelf and slope processes (3002)
DE: 4255 Numerical modeling (0545, 0560)
DE: 4553 Overflows
DE: 4568 Turbulence, diffusion, and mixing processes (4490)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005