Acoustic damping for explicit calculations of fluid flow at low Mach number

Technical Report · Wed Jan 01 04:00:00 EST 1986

DOI:https://doi.org/10.2172/6100813· OSTI ID:6100813

Ramshaw, J D; O'Rourke, P J; Amsden, A A

A method is proposed for damping the sound waves in explicit calculations of fluid flow at low Mach number, where sound waves are usually not of interest but may distract attention from other flow features. The method is based on the introduction of an artificial pressure q of the form q = - q/sub 0/rhoc/sup 2/..delta..t(del x u - del x u/sub 0/), where q/sub 0/ is a coefficient of order unity, rho is the density, c is the sound speed, ..delta..t is the time step, and u/sub 0/ is the velocity field that would obtain at zero Mach number. When del x u/sub 0/ is zero, the method becomes equivalent to the use of an artificial bulk viscosity q/sub 0/rhoc/sup 2/..delta..t. However, del x u/sub 0/ can be substantially different from zero in problems with heat or mass sources (e.g., combustion), and its inclusion is then essential to obtain the correct pressure field. The method is well suited for use in conjunction with explicit numerical schemes that employ acoustic subcycling or artificial reduction of the sound speed for improved efficiency at low Mach number. The beneficial effects of the method are illustrated by means of calculations with an acoustic subcycling computer program. 9 refs., 1 fig.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6100813
• Report Number(s): LA-10641-MS; ON: DE86007576
• Country of Publication: United States
• Language: English

Related Subjects

640410* -- Fluid Physics-- General Fluid Dynamics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ASPECT RATIO
COMPUTERIZED SIMULATION
DAMPING
FLUID FLOW
FLUID MECHANICS
MECHANICS
SIMULATION
SOUND WAVES