The numerical simulations of flows on a huge-scale are performed supposing a rotating stratified fluid so as to understand the effects of the interaction between flows and very large-scale obstacle. These include colioris forcing and a huge-scale obstacle in order that Rossby number is less than a unity, and the buoyancy frequency of the flow and mountain′s height are kept large in order Froude number with definition using mountain height keeps less than a unity. This situation includes the remarkable effects of stratification and rotation of the fluid, so the phenomena cause of interactions between flows and obstacle, concretely speaking a comparison the flow around mountain with over mountain and Taylor cap phenomenon, keep difficulties of understanding. A numerical model including primitive equations and no-slip boundary condition on bottom helps getting insights of a lot of effects, for example, the dynamical mechanism of a jet around a mountain and formation of an advecting cyclonic eddy near from mountain′s top.
To make clear these mechanisms and relation between the phenomenon and non-dimensional numbers of this fluid, further simulation are carried out with some values of the buoyancy frequency and wind speed. Results of these simulations clarify that (a) the jet flows separated to left and right on looking downward are kept by different reasons each other, one of the cause is concerned with the quasi-geostrophic flow pattern and another is concerned with the downdraft from higher level flow releasing the potential energy, (b) the maximum value of advecting cyclonic eddy depends on the upward flow speed and the buoyancy frequency, and shows that eddy is made of the tilting effect with quasi-geostrophic theory and the horizontal shear by the confluent jets at leeward.
These results have the applicability to the understanding of the flow pattern near an actual huge mountain and of the phenomena in the mid latitude. |
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