The viscous and pressure gradient terms, which can be solved by Green Function method theoretically, are calculated separately in MPS method. Through the analysis of kernel function, an accuracy condition of viscous t...
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The viscous and pressure gradient terms, which can be solved by Green Function method theoretically, are calculated separately in MPS method. Through the analysis of kernel function, an accuracy condition of viscous term is proposed and the reasonable match between spatial and time step will increase the accuracy and stability of MPS method. Poiseuille flow is simulated and the accuracy condition is validated. In the analysis of the source term of Pressure Poisson equation, the particle number density (PND), which is very sensitive to the relative configuration of particles, yields the deviation of velocity profile from the theoretical solution. It is the fluctuation in PND that causes the spurious fluctuation of pressure.
Granular materials are ubiquitous in nature and engineering. They display both fluid- and solid-like behavior with fascinating complexity and remarkable uniqueness. Their behavior at different scales is strongly coupl...
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Granular materials are ubiquitous in nature and engineering. They display both fluid- and solid-like behavior with fascinating complexity and remarkable uniqueness. Their behavior at different scales is strongly coupled with each other because of high nonequilibrium constraints and finite size effects.
The heat exchange tube with inner and outer fins has been widely applied in industry in order to enhance the performance of heat exchangers. When it is used in high temperature environment, the security must be consid...
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Experimental study of air natural convection in horizontally-positioned copper metallic foams with open cells was conducted. Temperature distributions on the heating surface were tested under different heating power f...
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ISBN:
(纸本)9781612847498
Experimental study of air natural convection in horizontally-positioned copper metallic foams with open cells was conducted. Temperature distributions on the heating surface were tested under different heating power for foam samples having different porosities and pore densities. The effects of porosity and pore density on the total thermal resistance of the foam sample were quantified. It is found that the porous surface can enhance the natural convection and reduce the thermal resistance by about 20% in comparison with a smooth surface. The surface area density and mass flow rate in natural convection are affected by porosity and pore density simultaneously. When the porosity is relative small (ε = 90%), there exits a critical value of the Gr number (turning point) for two pore densities (10ppi and 40ppi). When the Gr number is less than this critical value, the foam with a higher pore density has the lower total thermal resistance, whereas when the Gr number exceeds the turning point value, the opposite holds. If the porosity is increased to ε = 95%, the foam with a higher pore density has the lower thermal resistance in the whole experimental range. When the porosity and pore density is the same, the foam with smaller size has the higher thermal resistance in the whole experimental range. If the size is relatively small (100×100×50mm), for the two pore densities studied (20ppi and 80ppi), there exits a critical value of the Gr number (turning point). The foam with a lower porosity (ε = 90%) has the lower thermal resistance and the decrease is more obvious for the case of 80ppi. If the size is relatively big(100×100×80mm), there exists a critical value of the Gr number (turning point) only for the case of 10ppi. When the Gr number is less than this critical value, the foam with a higher porosity (ε = 95%) has the higher total thermal resistance, the opposite holds. While for the other two pore densities (20ppi and 40ppi), there is no turning point. The foam with
Bone tissue functions in varied mechanical systems of the body under static and dynamic conditions. Therefore, it is essential to understand the mechanical responses of bone at varied loading rates, especially those a...
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This paper studies the projectile electron loss cross sections of C^3＋ colliding with atomic hydrogen in the frame work of extended over-barrier model at intermediate velocities （25 keV/u-600 keV/u）. The electron l...
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This paper studies the projectile electron loss cross sections of C^3＋ colliding with atomic hydrogen in the frame work of extended over-barrier model at intermediate velocities （25 keV/u-600 keV/u）. The electron loss is calculated in terms of the interaction between the screened target nucleus and the active projectile electron and of the interaction between projectile electron and target electron. Compared with the convergent close-coupling calculations, screening and anti-screening calculations, this model satisfactorily reproduces the experimentally obtained energy dependence of the electron-impact ionisation cross sections and the single electron loss cross sections over the energy range investigated here.
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