Acoustic boundary layers as boundary conditions

Assessment of inflow boundary conditions for compressible turbulent boundary layers

A description of different inflow methodologies for turbulent boundary layers, including validity and limitations, is presented. We show that the use of genuine periodic boundary conditions, in which no alteration of the governing equations is made, results in growing mean flow and decaying turbulence. Premises under which the usage is valid are presented and explained, and comparisons with the...

Boundary conditions as constraints

A new method to compute the symplectic structure of a quantum field theory with non trivial boundary conditions is proposed. Following the suggestion in [1, 2], we regard that the boundary conditions are second class constraints in the sense of the Dirac’s method. However, we show that this proposal is more useful if we consider an inverse of the Holographic map between a theory defined in the ...

Boundary Conditions for Room Acoustic Simulations

Research on room acoustic simulation focuses on more accurate modeling of wave effects in rooms. Today, also wave models (e.g., the boundary element method and the finite differences in time domain technique) can be used for higher frequencies, thus, in the geometrical acoustics (GA) domain. Simulations in architectural acoustics are powerful tools but their reliability depends on the input dat...

Boundary Conditions as Dirac Constraints

In this article we show that boundary conditions can be treated as Lagrangian and Hamiltonian primary constraints. Using the Dirac method, we find that boundary conditions are equivalent to an infinite chain of second class constraints which is a new feature in the context of constrained systems. We discuss the Dirac brackets and the reduced phase space structure for different boundary conditio...

Admissible Boundary Conditions and Stability of Boundary-layers for a Hyperbolic Relaxation System