排序方式: 共有38条查询结果,搜索用时 125 毫秒
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采用八叉树结构 ,生成复杂外形绕流计算的非结构直角网格。物面附近用投影方法 ,使网格贴体。并将Jameson的有限体积法推广用于这种网格的欧拉方程计算。对歼击机模型的绕流计算表明 ,网格生成的机时花费很少 ,总体质量好 ,因而欧拉方程解算的收敛质量也好。 相似文献
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用非结构直角网格和欧拉方程计算运载火箭绕流 总被引:1,自引:0,他引:1
采用八叉树结构,物面附近用投影法,生成运载火箭绕流计算的非结构直角网格。并将Jameson的有限体积法推广用于这种网格的欧拉方程计算。算例表明,网格生成的时机化费很少,质量好;欧拉方程解算的收敛质量也好。 相似文献
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Sofya A. Ushakova Alexander A. Tikhomirov Valentin N. Shikhov Jean-Bernard Gros Tamara K. Golovko Igor V. Dal’ke Ilya G. Zakhozhii 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The main objective of a life support system for space missions is to supply a crew with food, water and oxygen, and to eliminate their wastes. The ultimate goal is to achieve the highest degree of closure of the system using controlled processes offering a high level of reliability and flexibility. Enhancement of closure of a biological life support system (BLSS) that includes plants relies on increased regeneration of plant waste, and utilization of solid and liquid human wastes. Clearly, the robustness of a BLSS subjected to stress will be substantially determined by the robustness of the plant components of the phototrophic unit. The aim of the present work was to estimate the heat resistance of two plants (wheat and lettuce) grown on human wastes. Human exometabolites mineralized by hydrogen peroxide in an electromagnetic field were used to make a nutrient solution for the plants. We looked for a possible increase in the heat tolerance of the wheat plants using changes in photosynthetically active radiation (PAR) intensity during heat stress. At age 15 days, plants were subjected to a rise in air temperature (from 23 ± 1 °C to 44 ± 1 °С) under different PAR intensities for 4 h. The status of the photosynthetic apparatus of the plants was assessed by external СО2 gas exchange and fluorescence measurements. The increased irradiance of the plants during the high temperature period demonstrated its protective action for both the photosynthetic apparatus of the leaves and subsequent plant growth and development. The productivity of the plants subjected to temperature changes at 250 W m−2 of PAR did not differ from that of controls, whereas the productivity of the plants subjected to the same heat stress but in darkness was halved. 相似文献
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V. G. Vil’ke 《Cosmic Research》2010,48(3):273-282
A mechanical system consisting from N deformable spheres interacting according to the law of gravity is considered as a model of planetary system. Deformations
of the viscoelastic spheres are described according to the model of the theory of elasticity of small deformations, the Kelvin-Voigt
model of viscous forces, and occur under the action of gravitational fields and fields of centrifugal forces. Approximate
equations describing motions of the centers of mass of the spheres and their rotations relative to the centers of mass are
constructed by the method of separation of motions on the basis of solving quasistatic problems of the theory of viscoelasticity
with allowance made for smallness of sphere deformations. Using the first integral of conservation of the angular momentum
of the system relative to its center of mass, the expression for the changed potential energy is obtained with the use of
the Routh method. An investigation of stationary rotations is carried out, and it is shown that all of them are unstable,
if the number of planets is more than two. 相似文献
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Translational-rotational motion of three planets modeled by viscoelastic balls in the gravitational field of mutual attraction
is studied in this paper. The system of equations of motion for the mechanical system under consideration is deduced from
the d’Alembert-Lagrange variational principle. Using the method of separation of motions, an approximate system of ordinary
differential equations, describing the translational-rotational motion of the planets, is obtained with taking into account
perturbations caused by elasticity and dissipation. The found steady-state motion of the system is an analog to triangular
libration points in the classical three-body problem. 相似文献
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证明了任意二维物体能捕捉到的驻定态自由涡最多只有中性稳定性;物表面用抽无助于稳定性。如果有一点源能与自由涡相联,有可能使驻定态自由涡达到真正稳定。 相似文献