Modeling Method and CFD Simulation of a Hypersonic Cruise Vehicle

In order to solve the problems in complex terrain modeling by computational fluid dynamics(CFD) simulation at prophase, such as difficulty in collecting data, tedious modeling process, wasting times and so on. In this paper, combined various commonly digital technology，and the transformation between the network terrain file and CFD (PHOENICS) solid model is realized by using a new set of outdoor complex terrain rapid digital modeling method. Take mountain city -Chongqing as an object to analyses the near-surface wind environment. The method is directly generated by the network terrain data without any screening or simplified. The virtual model can be matched the actual terrain with the extreme. By using the simulation cycle for complex terrain, time will be greatly shortened for urban planning.

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Modeling and Validation of the Cool Summer Microclimate Formed by Passive Cooling Elements in a Semi-Outdoor Building Space

Sustainability ◽

10.3390/su12135360 ◽

2020 ◽

Vol 12 (13) ◽

pp. 5360

Author(s):

Maria Alejandra Del Rio ◽

Takashi Asawa ◽

Yukari Hirayama

Keyword(s):

Natural Ventilation ◽

Cfd Simulation ◽

Field Measurements ◽

Modeling Method ◽

Passive Cooling ◽

Indoor Space ◽

Effective Combination ◽

Cool Summer ◽

Cooling Element ◽

Del Rio

Previous measurements (Del Rio et al. 2019) have confirmed the formation of cool summer microclimates through a combination of passive cooling elements (i.e., evaporative cooling louver, vegetation, and sunscreen) in semi-outdoor building spaces in Japan. Computational fluid dynamics (CFD) simulation is useful to understand the contribution of each element to semi-outdoor and indoor microclimates with natural ventilation, and to determine their effective combination. To date, there have not been sufficient studies on the modeling and validation for the CFD simulation of microclimates by such elements. This study demonstrates the modeling method using literature-based values and field measurements. It also demonstrates model validity by comparing the obtained results with field measurements. The results show that CFD simulation with detailed modeling of these elements can replicate vertical temperature distributions at four different positions across the semi-outdoor space and indoor space. The maximum difference in air temperature between the measurements and simulation results was 0.7–1 °C. The sensitivities of each passive cooling element on the microclimates formed in both spaces were confirmed. The watered louver condition and shorter louver–window distance were most effective in cooling both spaces. These results indicate that the modeling method could be effectively applied to assess cool microclimates and formulate a passive cooling design.

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High-Precision Dynamics Characteristic Modeling Method Research considering the Influence Factors of Hydropneumatic Suspension

Shock and Vibration ◽

10.1155/2020/8886631 ◽

2020 ◽

Vol 2020 ◽

pp. 1-21

Author(s):

Wenguang Wu ◽

Hongliang Tang ◽

Sha Zhang ◽

Lin Hu ◽

Fanhao Zhang

Keyword(s):

Cfd Simulation ◽

Ride Comfort ◽

Fluid Dynamic ◽

Influence Factors ◽

Kriging Model ◽

Modeling Method ◽

Effect Of Temperature ◽

Oil Viscosity ◽

Nonlinear Characteristics ◽

And Control

In recent years, hydropneumatic suspension (HPS) has come into widespread use for improving the ride comfort and handling of mining dump trucks and off-road vehicles. Therefore, it is critical to improve the mathematical modeling accuracy to enhance the design and control efficiency and accuracy of HPS. This paper aims to propose a model for improving the modeling precision by considering the effect of different factors on HPS characteristics. A computational fluid dynamic (CFD) model of a HPS was developed, and the volume of fluid (VOF) method was used for the transient calculations in order to simulate the fluid dynamic characteristics and determine the damping and stiffness forces of HPS. The effect of temperature, oil viscosity, nitrogen dissolution rate, and suspension vibration speed on the nonlinear characteristics of HPS was investigated. A limited number of simulation sample points were designed based on the variation ranges of the above factors using the design of experiment (DOE) method. The corresponding damping and stiffness force of each sample point were calculated by CFD simulation. The obtained simulation data were utilized for the fitting of a Kriging model. The results demonstrated that the Kriging model can provide high accuracy, with a prediction error lower than 5%. The proposed modeling method of the HPS nonlinear characteristics is highly efficient, accurate, and faster than traditional methods.

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