جستجوی مقالات مرتبط با کلیدواژه « conservative » در نشریات گروه « مکانیک »

Two-fluid models are the most accurate and complex models for analysis of two-phase flows. There are two different two-fluid models for analyzing compressible isothermal two-phase flows which are Single Pressure Model (SPM) and Two-Pressure Model (TPM). In spite of capabilities of these models in capturing two-phase flow behavior، it is not possible to express them in conservative form due to existence of non-conservative term in momentum equation of phases. Therefore، the classical Rankine-Hugoniot condition across discontinuities in the flow filed is not applicable for these equations and there would be difficulty in using classical numerical methods for solving these equations. In this paper a new path-conservative method is used to overcome this difficulty. In this method، one can apply general Rankine-Hugoniot condition along a path connecting left and right states of the discontinuity. After expressing path-conservative form of the employed central numerical methods which are Lax-Fridriches، Lax-Wendroff and Rusanove، water faucet and large relative velocity shock tube problems are solved by using these schemes. Grid independence was achieved using different grid sizes. For water faucet problem، comparison of numerical results with analytical solution show good agreement and for shock tube problem، the results indicate that this method is highly capable in capturing discontinuities in two-phase flow.

In this paper, dynamic stability of two free-end beam subject to a non-conservative following force has been investigated. In the first step, transverse vibration of beam structure in free-free mode with/without end force by modal analysis and FEM was analyzed and mode shapes and natural frequencies were obtained. Then, dynamic equations of the vibration with using the Galerkin method were solved. It can be seen that with increasing the axial force frequency of transverse the vibration of the beam decreased. Also, flutter phenomenon in the states of axial force much higher than buckling force is observed. Furthermore, in case of non-uniform beam, in free-free mode both flutter and divergence are occurred. It can be concluded that, due to low thrust weight ratio in nowadays flying objects, the effect of flutter on dynamic stability of structure itself is not significant. However, the effect of joint in beam significantly reduces the critical force of flutter.