A micro-kinetic model of enhanced foam stability under artificial seismic wave

To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability,a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wave is established based on a vertical liquid film drainage model and elastic wave theory.The model is solved by non-dimensional transformation of the high order partial differential equations and a compound solution of implicit and explicit differences and is verified to be accurate.The foam film thickness,surfactant concentration distribution and drainage velocity under the action of low frequency artificial seismic wave are quantitatively analyzed.The research shows that low-frequency vibration can reduce the difference between the maximum and minimum concentrations of surfactant in the foam liquid film at the later stage of drainage,enhance the effect of Marangoni effect,and improve the stability of the foam liquid film.When the vibration frequency is close to the natural frequency of the foam liquid film,the vibration effect is the best,and the best vibration frequency is about 50 Hz.The higher the vibration acceleration,the faster the recovery rate of surfactant concentration in the foam liquid film is.The higher the vibration acceleration,the stronger the ability of Marangoni effect to delay the drainage of foam liquid film and the better the foam stability is.It is not the higher the vibration acceleration,the better.The best vibration acceleration is about 0.5 times of gravity acceleration.Reasonable vibration parameters would greatly enhance the effect of Marangoni effect.The smaller the initial concentration of surfactant,the better the vibration works in enhancing Marangoni effect.

Efficient Procedure for Seismic Analysis of Soil-Structure Interaction System

A simplified and efficient procedure, based on the viscous-spring artificial boundary and the modal superposition method, is developed to analyze the dynamic soil-structure interaction system in the time domain. The viscous-spring artificial boundary introduced in this procedure transforms the infinite soil-structure interaction system to an approximately finite system. A seismic wave input method is used to transform the wave scattering problem into the wave source problem. The modal superposition method is then applied to this approximate finite system. The results show that this method with only a few modes can significantly reduce the computational time with almost the same precision as the traditional direct integration method. Comparison of results from different loading times demonstrates that the advantages of this method are evident in computing with long loading time.