Turbulence of Capillary Waves on Shallow Water

We consider the developed turbulence of capillary waves on shallow water. Analytic theory shows that an isotropic cascade spectrum is unstable with respect to small angular perturbations, in particular, to spontaneous breakdown of the reflection symmetry and generation of nonzero momentum. By computer modeling we show that indeed a random pumping, generating on average zero momentum, produces turbulence with a nonzero total momentum. A strongly anisotropic large-scale pumping produces turbulence whose degree of anisotropy decreases along a cascade. It tends to saturation in the inertial interval and then further decreases in the dissipation interval. Surprisingly, neither the direction of the total momentum nor the direction of the compensated spectrum anisotropy is locked by our square box preferred directions (side or diagonal) but fluctuate.

Turbulence of Capillary Waves on Shallow Water

We consider the developed turbulence of capillary waves on shallow water. Analytic theory shows that an isotropic cascade spectrum is unstable with the respect to small angular perturbations, in particular, to spontaneous breakdown of the reflection symmetry and generation of nonzero momentum. By computer modeling we show that indeed a random pumping, generating on average zero momentum, produces turbulence with a nonzero total momentum. A strongly anisotropic large-scale pumping produces turbulence whose degree of anisotropy decreases along a cascade. It tends to saturation in the inertial interval and then further decreases in the dissipation interval. Surprisingly, neither the direction of the total momentum nor the direction of the compensated spectrum anisotropy is locked by our square box preferred directions (side or diagonal) but fluctuate.

Research on Torsional Property of Body-In-White Based on Square Box Model and Multiobjective Genetic Algorithm

In order to assess the performance of a vehicle in the conceptual design stage, a square box model was proposed to predict the torsional stiffness and the first-order torsional frequency of Body-in-White. The structure of Body-in-White was decomposed into eight simple structural surfaces, from which a square box model was constructed. Based on the finite element method, modified shear stiffness of each simple structure surface was calculated and the torsional stiffness was obtained. Then, simple structural surfaces of Body-in-White were constructed into an eight degree-of-freedom series spring system to calculate the first-order torsional frequency. Furthermore, a multiobjective genetic algorithm was used to determine the thickness and structural reinforcement of panels with small stiffness, so as to achieve the goal of increasing the stiffness while reducing the mass of the panel. The result shows that the optimal values of thickness are reduced by around 9.9 percent without affecting their performance by the proposed method. Compared to the prediction results obtained with the complicated numerical simulation, the relative error of the square box model in predicting the torsional stiffness is 6.04 percent and in predicting the first-order torsional frequency is 0.95 percent, indicating that the prediction model is effective.

Effects of Moisture Content and Compaction Pressure on Bulk Density of Rye

HighlightsRye grain compaction was measured for three different moisture contents (8%, 12%, and 16% wet basis) at five different compaction pressures (7, 14, 34, and 55 kPa)Bulk densities were found to be statistically significantly dependent (p < 0.0001) on both the moisture content and applied pressure.Compacted bulk densities increased with increasing applied pressure for all moisture contents.Abstract. Bulk density of agricultural grains is needed to determine the quantity of grain in storage structures and to calculate grain pressures. The objective of this study was to investigate the effects of moisture content and applied pressure on bulk density of rye grain at moisture contents and pressures typical of those seen in storage structures. Rye compaction was measured for three moisture contents (8%, 12%, and 16% wet basis) at four compaction pressures (7, 14, 34, and 55 kPa) using a square box (based on the design used by Thompson and Ross, 1983). Data from the compaction tests were used to calculate the bulk densities for the three moisture contents and four compaction pressures. The bulk densities were found to be significantly dependent (p <0.0001) both on moisture contents and the pressure applied. Bulk densities varied with increasing moisture content as has been observed in similar studies for rye and other agricultural grains such as wheat and soybeans. These results provide guidance for estimating bulk density of rye in bins and other storage structures. Keywords: Grain compaction, Grain storage, Kernel rearrangement, Kernel elasticity.