Numerical Dissipation and LES
Presence of non-linear terms leads to aliasing errors
Aliasing errors can result in accumulation of energy and lead to instability
Common approach to damping aliasing errors is to add dissipation (artificial viscosity or upwinding)
- Artificial viscosity will not only damp aliasing errors but also damp small scales of the flow
Alternative approach is to use energy-conserving schemes
- Schemes achieve stability without adding dissipation
- 2nd-order central scheme on staggered mesh is conservative
- Higher order schemes are also available (Morinishi et al. 1998)
These schemes are not as “robust” as dissipative schemes