|How Dissipation and Free Boundary Layers Can Be Better Handled in the SPH Approach
|444, 5th International Conference of Numerical Modeling of Space Plasma Flows (ASTRONUM 2010)
|Lanzafame, G.; Costa, V.; Belvedere, G.
|A recent reformulation of the equation of state (EoS) for ideal flows is here applied for accretion disc flows.
Such an EoS, correctly describing shear flows, also includes the physical dissipation necessary to handle shock
fronts and discontinuities in the flow for non reversible physical events. It is also recently shown that the chosen
SPH Kernel deeply affects the particle interpolation integrals. A Gaussian SPH in extended range (GASPHER)
interpolation Kernel, originated from the Error function (and Gaussian integrals), better deals with both free
edge boundary layers difficulties, as well as any spatial transport phenomenon, better conserving the total energy.
According to such new approaches, some examples on accretion disc models in close binaries (CBs) are here reported.
According to the new implementations, the physical dissipation alone, included in the EoS, cannot be responsible
of the transport mechanism engine producing a well bound accretion disc in an inviscid Euler scheme. Periodical
phases of mass accumulation and loss characterize non viscous discs. Therefore, a physical turbulent viscosity
is necessary to form well bound discs in a Navier–Stokes scheme.