Microscopic modeling of sound waves in granular material: Quarterly progress report, 1/1/87-3/31/87
As a preliminary to the study of sound waves themselves, we have looked at test cases of particles contained within vibrating boxes. The vibration amplitudes were larger than would occur in most sound-wave problems, but observed particle behavior could be compared against behavior seen in similar calculations performed with a completely independent particle-dynamics code (Haff and Werner, 1986). These comparisons provide one line of argument supporting the notion that the present code is correctly computing the motion of particles in the presence of an external energy source. Some comparisons have also been made against particle motion observed in the laboratory in a two-dimensional shaking box, with satisfactory agreement. A one-dimensional array of particles is being constructed which will be driven acoustically with a piezoelectric transducer. This will allow us to compare code predictions with one of the simplest possible particle configurations capable of transmitting acoustic waves. These and similar comparisons will also allow a calibration of the simulation model, and will help us determine allowable ranges of material ''constants'' which cannot otherwise easily be pinned down. We will begin some simple acoustic simulations in which a sample of approx.100 particles is enclosed in a container at known pressure and a periodic elastic wave signal is fed into the system at one boundary and detected at another. This simple system will suffice for preliminary studies of the effects on wave speeds and attenuation of external variables such as pressure, and internal variables, such as grain properties, packing-geometry, and so forth.
- Research Organization:
- California Inst. of Tech., Pasadena (USA)
- DOE Contract Number:
- FG22-86PC90959
- OSTI ID:
- 6676798
- Report Number(s):
- DOE/PC/90959-T1; ON: DE87007400
- Country of Publication:
- United States
- Language:
- English
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