Reference : Overshootings and spurious oscillations caused by biharmonic mixing
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
Overshootings and spurious oscillations caused by biharmonic mixing
Delhez, Eric mailto [Université de Liège - ULiège > Département d'aérospatiale et mécanique > Mathématiques générales >]
Deleersnijder, Eric [> > > >]
Ocean Modelling
Elsevier Science
Yes (verified by ORBi)
United Kingdom
[en] numerical model ; ocean dynamics ; monotonicity ; positiveness ; biharmonic mixing
[en] Biharmonic mixing is often used in large scale numerical models of the ocean because of its scale selectivity; it effectively damps small scale noise and leaves the large scale dynamics nearly unaffected. The biharmonic operator lacks however positiveness and monotonicity and can therefore produce unphysical results exhibiting spurious overshootings and oscillations. This problematic behaviour cannot be avoided by the addition of an ordinary Laplacian diffusion term. It appears in both continuous and discrete approaches/solutions in both unbounded and bounded domains. The overshootings and oscillations are induced by the strong damping of the smaller scale modes and are therefore comparable to the Gibbs' phenomenon. With appropriate boundary conditions, the variance of the field decreases monotonically and the oscillations are expected to remain small. The lack of positiveness is however a severe drawback for (dynamic) tracer studies. (C) 2007 Elsevier Ltd. All rights reserved.
Centre Interfacultaire de Recherches en Océanologie - MARE

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