在数值模拟的离散方程中,一阶导数偏差分格式是什么?它和中心差分格式有什么区别?

你是在模拟旋转机械吧?估计你是想模拟单流道吧?切块没切好或者周期面没设置好

如果是连续性无法收敛的话一般是网格质量不行,你的网格存在尖点,网格斜率大于0.8了,建议你从新划分网格,划分网格的时候分区划分,将尖点处单独划分 ,稍密一点 这样可能会好点.

模拟,用通俗的话来说,就是用近似的简化的模型或者数据,去模仿真实的情况,并试图找出最简单的办法去解决现实中的问题.

周期性是不能在icem里面设置的,如果你想用conformal方法,只要保证两个界面上的网格完全一样就可以了,如果要求低,直接画,什么也不用管,到fluent或者cfx里面可以设置interface方法.

高陡边坡：high and steep side slope
the numerical simulation of excavation and support of high & steep side slopes on cable-crane platform,

EPC casting has such distinguishing features as high production efficiency,high precision,good product quality ,less polluting and so on.This paper will focused on the aluminum alloy cylinder , a numerical simulation will be carried out for the mould and solidifaction of cylinde block EPC casting ,based on ProCAST,a numerical simulation software,and a optimal process plan will be determined to shorten the test cycle, save production costs, improve product quality, so as to guide the actual production.
The most important and largest part of a engine is the cylinde block . Because of the complication of the structure and the uneven of the wall thickness of the cylinde block,this is the focus and the difficult part of the engine production, the casting of the cylinde block is directly related to the level of the quality of the engine.This paper analyzes the cylinder block structure, two types of gating system are designed: top gating system and step gating system.As a result of simulating both the filling and solidification process,comparing to the temperature of the flow field and the predict of shrinkages and macroporosity of the two gating systems,we found that top gating system is relatively stable when filling, solidification temperature gradient is smaller, distribution is more uniform, cooling speed is faster, is good for reducing the thermal stress, refining grain , geting uniformly distributed organizational structure. So the top gating system is more reasonable. Rearch
Then, the impact between temperature,pattern density ,vacuum degree with shrinkages and macroporosity of the cylinde block has been carried out in this paper.Studies showing:
three factors impact the defect in a decreasing order is density, pouring temperature, vacuum degree. The combination of the minimum propensity to form casting shrinkage and macroporosity is pouring temperature of 730 ℃, vacuum degree of 30kPa and pattern density of 18g / L.
Therefore, this paper determine the final process paln. For the EPC casting of the aluminum alloys cylinde block （ZL101） , we adopt the EPS (polystyrene) as the pattern materials, select the top gating system, casting temperature is 730 ℃, vacuum degree is 30kPa and pattern density is 18g / L.

PS 花了两小时,每句看过,希望有点用处.

Using numerical simulation method is used to study with rudder catheter propeller open water performance, can partly replace model test, so as to reduce the catheter propeller design cost, shorten the design cycle, in order to optimize the catheter screw propeller provide a feasible way. This paper derived the propeller blade section local coordinate system to the global coordinate system and the coordinate conversion formula, and gives the 3 d entity modeling process.
Using the computational fluid mechanics software to viscous flow field in open water propeller hydrodynamic performance calculation research, simulate the catheter propeller in different into speed coefficient of the thrust coefficient, torque coefficient, propeller surface pressure distribution and propeller after wake field condition, etc. Then will open water performance of the numerical calculation results and map the calculation results do a comparative analysis. Through the comparative analysis with the test pattern, found Wilcoxk - ω model is more suitable for catheter propeller open water performance calculation, and use structured grid and unstructured grid calculation method of combination can meet the catheter propeller open water performance forecast accuracy requirement of the engineering. In addition, if you want to get more accurate calculation results, we should improve the quality of grid, as far as possible to use structured grid. Although the grid number of increase is not always mean calculation error reduction, but reasonable control grid fine density can get more credible computational results.