Loading...

Theoretical and Numerical Analysis of Shock Waves Propagation in Porous Medium

Nemati Hayati, Ali | 2013

2729 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 44592 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ahmadi, Mohammad Mehdi; Mohammadi, Soheil
  7. Abstract:
  8. Particulate porous mateials have always been of interest in terms of reducing shock waves effects in different protective applications. Therefore, the physics governing the flow in porous media is especially significant for which different models have been presented by the researchers. The complexities of these media have caused many existing models to be unable to properly predict the behavior of granular media under shock loadings. On the other hand, the complexity of the equations makes the numerical solution of them cumbersome and costly in a way that many researchers do not solve the whole coupled equations and reduce their number. In addition, current high-resolution TVD solutions of these equations require the calculation of eigenvectors from the jacobian matrix, which is practically impossible even in the one-dimensional case. This offen puts burden of the numerical solution of shock waves propagation in porous media. In this thesis, for the first time, the prediction of the effects of different geometrical parameters of the granular material, namely particle diameter, shape and arrangement, in the overall behavior of the medium has been made possible by presenting a volume averaging theory. Using this theory, the highly-significant Forchheimer equation in porous materials was reinvestigated, leading to a new framework generalizing the previous findings. Also, a simplified solution for weak shock wave propagation in isothermal shock tube is described for the first time, which illustrates how field parameters such as gas velocity, pressure and density along with the shock speed are affected by these parameters. The governing equations of the gas and porous material are subsequently studied and improved by modifying the source terms. Second-order velocity terms, viscosity and their resulting dissipation have been incorporated in the equations using the volume averaging theory. To overcome the difficulties in the numerical solution of the equations, a Finite Volume method has been introduced for the first time which enables the high-resolution TVD solution of the coupled equations without the need for eigenvectors. In this regard, a FORTRAN code has been written to solve the shock tube problem and compared with the experimental results for which good coherence is found. Consequently, using an extensive set of numerical experiments on the influential parameters and by suggesting a new non-dimensional parameter named 'effective filter length', a new equation has been proposed for predicting the efficiency of the protective granular filter against the incoming shock, which can be used effectively in protective measures in different applications
  9. Keywords:
  10. Shock Wave ; Porous Medium Equation ; Volume Averaging Method ; Shocke Tube ; Surface Protection

 Digital Object List

 Bookmark

...see more