共查询到20条相似文献，搜索用时 31 毫秒
1.
Based on the fluid saturated biphasic porous media model deduced from mixture theory,a finite element formulation with u S u F p variables for dynamic response analysis is given out.This method overcomes the difficulty of choosing suitable penalty parameter in penalty finite element method,and the accuracy of pressure distribution obtained with the mixed finite element method is higher than the penalty finile element method.An iterative solution method is suggested to solve the system of equations whose coefficient matrices are non positive definite.It is concluded from patch test that the order of interpolation function for pressure variables must be higher than that of displacement variables of solid phase. 相似文献
2.
Biphasic porous medium model,based on the mixture theory in continuum mechanics frame,is used to depict the distributing disciplinarian of sclerotin's stress field,distortion field and pore pressure when the bone tissue is subjected to various dynamic loadings.The coupling relationship among the distortion,fluid flow and the streaming potential is studied.The penalty finite element formulation for streaming potential is studied.The penalty finite element formulation for streaming potential distributing in bone tissue is obtained by using Galerkin weighted residual method for the biphasic porous medium model with corresponding initial and boundary conditions,in this modeling,the solid phase is assumed to be isotropic elastic medium,and the fluid phase is ideal fluid.The computational results show that because of the distortion of bone tissue the marrow's flow is raised,then the electriferous partical moves in the porous and the streaming potential appears. 相似文献
3.
An extended finite element method based on SUPG/PSPG is proposed to simulate the two phase flow problems. A corrected XFEM is introduced to ensure the blending element to satisfy the Partition of Unity in processing the discontinuity of the interface. Level set method is adopted to track the kinetic phase interface as the fluid flow. Free oscillation is numerically simulated with the presented method. The obtained numerical results are in consistent with the analytical and experimental results. Additionally, breaking dam problem is considered, the numerical solutions agree well with experimental results which illustrate the correctness and efficiency of the proposed method. No re-meshing is needed during the simulation of the two phase fluid flow and the moving interface can be accurately tracked by means of the presented method. 相似文献
4.
Investigation on flow and heat transfer characteristics in capillary porous wick based on alkali metal thermal-to-electric converter (AMTEC) 总被引：1，自引：0，他引：1
An axial symmetric invariable temperature phase change interface model of capillary porous wick based on alkali metal thermal-to-electric converter (AMTEC) is established to simulate flow and heat transfer characteristics in capillary porous wick and liquid channel by solving the mass and heat transport controlling equations. The effects of the working fluid flow rate, inlet temperature, porous wick thickness, porosity and effective pore diameter on the distributions of pressure, velocity and temperature are analyzed. In addition, the available effective pore size of the porous wick and the measures to improve the performance of the porous wick are given by analyzing the relationship between the maximum available capillary pressure and the loop pressure drop. The results show that the model presented in gives a good agreement with the three dimensional two-phase evaporation model. The flow and heat transfer characteristics of the capillary porous wick with the alkali metal liquid as working fluid are different from that with the traditional working fluid in some ways. 相似文献
5.
Linear boundary element method is used for the analysis of viscous fluid. The velocity components and the fluid mean pressure are taken as unknown functions. The comparison of linear BEM with constant BEM shows that the former presents much better precision and better convergence. 相似文献
6.
Articular cartilage, which is composed with a solid phase of collagen fibers and proteoglycan and a pore fluid phase, can be depicted with two-phase porous medium model based on mixture theory. This paper analyzed the creep and stress relaxation responses of confined compression problems of articular cartilage with the developed finite element method. The obtained responses of velocities of both solid and fluid phases and the effective stresses of solid phase as well as the pore pressures during the creep and stress relaxation processes of articular cartilage tissues under confined compression can be used as a theoretical reference for man-made cartilage materials, and behave important significance for the research in bio-mechanical engineering area. 相似文献
7.
This paper analyzes the fluid flow and heat transfer of the heat exchanger, and obtainsd the distribution of fluid field, heat field and pressure field in heat exchanger. According the analysis result, some modify measure is adopted, such as decreasing the number of tube bundle, the size of baffle plate and increasing the diameter of exchange heat tube. In the new heat exchanger, the resistance decreased 32.3%, is 103.2 Pa and the temperature of the exit is 130 K. The new heat exchanger satisfies the requirement of exchanging heat. The study indicates that adopting the numerical simulation method could get temperature, pressure and fluid - velocity of anywhere of the heat exchanger, and understand effecfing of structure parameter on fluid flied and heat flied of the heat exchanger. Therefore, it provides a new method for optimization design of heat exchanger. 相似文献
8.
刺葡萄籽油萃取及成分分析研究 总被引：2，自引：0，他引：2
以刺葡萄种籽为原料,采用普通超临界和超声波强化超临界萃取技术,对发酵、未发酵不同处理的刺葡萄种籽进行脂肪酸萃取,并用气相色谱—质谱联用仪对刺葡萄种籽油的化学成分进行了分析。结果表明,刺葡萄种籽油萃取的最佳工艺为萃取压力30 MPa,萃取温度35℃,分离温度55℃,分离压力12 MPa,在此条件下,普通超临界装置萃取的刺葡萄籽油萃取率高、油脂清亮且透明度好,优于超声波强化超临界装置。GC-MS分析显示,2种不同处理的刺葡萄籽油的成分都以脂肪酸为主,其中未发酵的刺葡萄籽油不饱和脂肪酸质量分数为87%,不饱和脂肪酸以亚油酸为主,质量分数为85.67%;发酵后的刺葡萄籽油不饱和脂肪酸质量分数为83%,不饱和脂肪酸以亚油酸为主,质量分数为82%,其油脂微浊,酸价较高,油质较不发酵的刺葡萄籽油脂低。 相似文献
9.
Zeng Shukun 《保鲜与加工》1988,(4)
This paper briefly introduces Patankar-Spalding Method, which is systematical, active and widely applicable in numerical heat transfer and fluid flow. The corresponding dependent variables, diffusivities and source terms for the general differential equations under all circumstances are explained. By using this method the calculation of two-dimentional Poiseuiue Flow and Couette Flow compared with exact solutions are proved to be high precision. with two-dimentional path-flow in the heat convertor intersification devices as an example, the tilted method is used with FORTRAN 77 programming, and the calculation is done on a SIEMENS 7570c minicomputer. 相似文献
10.
MAO Hong-xi BAI Chen-guang QIU Gui-bao CHEN Deng-fu WEN Liang-ying DONG Ling-yan 《保鲜与加工》2005,(6):52-56
Most of the former study for metallurgical molten slags (MS) was on the assumption that MS is newtonian fluid, and show lots of limitation. For the reasons such as the existence of gas-liquid phase points, MS shows a property of non-newtonian fluid. For this reason, the advances in some areas are conducted, including the measurement method, the factors influencing the MS and the viscosity computed models, which is prepared for the further research of the physical-chemical properties of blast furnace slag bearing titania. 相似文献
11.
灌浆规范中的灌浆压力是作用在灌浆岩体上的孔内灌浆压力。由于工艺的约束,现行灌浆监控过程常用孔口压力表示孔内灌浆压力,造成了灌浆压力的测量误差。针对非循环灌浆工艺,通过建立流体管道流动模型开展数值计算,采用多因素多水平正交法探究灌浆压力误差受浆液配比、浆液流速、灌浆孔深的相对影响,并采用统计法来分析不同工况下的显著影响因素。研究结果表明：灌浆压力较小时,灌浆压力误差普遍较大;若此时灌浆孔深且流速较大时,灌浆压力的测量误差则会超过灌浆压力仪表0.5%的精度要求,须进行误差补偿。其次,极差分析结果表明灌浆孔深是造成测量误差的主要因素,灌浆流速是第二个主要因素。而综合所有试验结果,浆液流速和灌浆孔深接近时,浆液配比越小,绝对偏差越大。结合上述正交试验和数值模型获取了不同工况下孔内灌浆压力值。 相似文献
12.
Considering the compression of medium and fluid, coupled vibration of saturated fractional derivative type viscoelastic soil and a circular tunnel with partially sealed shell lining in the frequency domain is investigated according to theories of Biot and elastic shell. The stress and displacement constitutive behavior of the soil skeleton is described by fractional derivative model which reflects the rheological properties of the medium while regarding soil as a liquid-solid saturated porous medium. The expressions of displacement, stress and pore water pressure are obtained while the inner boundary of circular tunnel is subjected to axially symmetric radial traction and axially symmetric fluid pressure respectively by introducing a partially permeable boundary condition. With the parameter analysis, it is revealed that the order of fractional derivative model on the responses for the system subjected to the symmetric radial traction is much greater than that of the system under the axially symmetric fluid pressure. And resonance phenomenon occurs obviously. Nevertheless the system responses do not have remarkable resonance phenomenon under axially symmetric fluid pressure. 相似文献
13.
采用超临界甲醇法制备大豆生物柴油 总被引：1，自引：0，他引：1
分析了超临界技术制备生物柴油的反应机理,重点阐述了温度、醇油比、压力、水和游离酸对超临界法制备生物柴油的影响。与其他化学法相比,超临界甲醇法的反应时间从1￣8h降低到4min,对原料油的要求也低,可使水含量及酸值较高的废油,未经处理即可制得转化率为98%以上的生物柴油。论述了反应机理,展望了超临界技术制备生物柴油的工业应用前景,并对超临界技术制备生物柴油的研究提出了建议。研究表明,采用超临界技术制备生物柴油,在反应时间、对原料要求和产物回收等方面均具有传统碱催化法无法比拟的优势。 相似文献
14.
High pressure processing (HPP) has been proposed as a potential quarantine method against the Mexican fruit fly (Anastrepha ludens), which parasitizes mango (Mangifera indica) fruit. It is efficient against this pest in conditions of high pressure and moderate temperatures. However, further studies are required to evaluate the effect of this quarantine treatment on fruit quality. The aim of this study was to evaluate the effect of HPP on the postharvest physiology of ‘Keitt’ mango during storage at 25 °C. Mangoes at physiological maturity were pressurized at 50, 70, and 90 MPa for 9 min (a control was obtained with no pressurization). The fruit were stored for 14 d and changes in physiological and physicochemical variables associated with ripening were assessed. The pressure level affected the respiration rate resulting in changes in other variables, such as total soluble solids. High pressure did not inhibit fruit ripening and the quality of the treated fruit was similar to that of the control. 相似文献
15.
Based on the analysis of dynamics method of pneumatic transmission, the mathematic model of air brake Load Sensing Proportional Valve (LSPV) is established by fluid servo control theory. The air brake LSPV of one All Terrain Vehicle (ATV) is simulated with the platform of advanced modeling ervironment for performing simulations of engineering system(AMESim), then the input and output pressure characteristic curve of the valves are obtained. The characteristic curve shows, with the load increasing, the pressure adjustment point of Load Sensing Proportional Valve (LSPV) moves up. When the pressure reaches into the pressure adjustment point, the increase rate of output pressure is less than the increase rate of input pressure, so that it can effectively prevent the lockup of the rear wheel precede the front wheel. The result of the simulation is consistent with the experiment result. The validity of the model is verified, which provide foundation for the simulation of the air brake elements and brake system. 相似文献
16.
机械通风降温效果的数值评估 总被引：8，自引：1，他引：7
地槽通风是机械通风的常用形式,是保证粮食安全储存和保持粮食品质的重要措施.常规的试验研究测量方法难以全面和准确评估设计的有效性和合理性.本研究利用计算机流动模拟的方法(CFD)对常用的U形地槽通风方案进行了数值研究,获得了风道中流速和压力分布的关键性数据,发现了与实际现象相符合的通风死角区域,同时又发现了常规测量手段中难以探测到的风道之间存在的通风薄弱区域,在理论上分析了存在通风死角和风道压力损失的原因.计算流体力学研究方法的运用可成为机械通风优化设计研究的有效工具,为今后机械通风应用技术的发展提供针对性和实用性的依据. 相似文献
17.
lIN Chang sheng 《保鲜与加工》2000,(6):34-36
The boundary element method was used for incompressible viscous fluid flow past a circular cylinder near a plane. The various phases of the flow passing the cylinder are studied numerically with different g/d. The numerical simulation of velocity fields is in good agreement with Davis' theoretical results and Taneda's experiments. In particular, the distributive curves of the surface force and the pressure on the circular cylinder were calculated numerically. 相似文献
18.
以万寿菊中的黄色素为研究对象,对影响超临界CO2流体萃取万寿菊黄色素的萃取温度、萃取压力和萃取时间分别进行了单因素研究。通过响应面最终确定最佳萃取条件为:萃取温度为60℃,萃取压力为48.6MPa,萃取时间为180min。在此条件下,万寿菊黄色素的最高得率为8.44mg/g,验证试验值为8.41mg/g,与预测值相对误差为0.36%。因此响应面法可以优化超临界萃取万寿菊黄色素工艺条件。 相似文献
19.
The correlation dimension for the time series of blast furnace process varisble,such as blast volume, burden pressure drop and blast pressure etc.,have been estimated by using GP and modified GP algorithms.The predictublity analysis for the process variables have also been investigated.The results show that it is difficult to determine the chaotic attractor of blast furnace condition.It has been found that the predictablity for process variables can be used to niterpret and identity the precursor of biast furnace condition. 相似文献
20.
Filling process of differential-pressure cast for thin-wall castings of aluminum alloy is simulated with the hydraulic simulation method. The effects on filling fluid pattern was taken by the figure and amount of the ingate and the wall width of castings are researched. It is shown that the wall width of castings has obvious effect on critical pressure increase rate and critical filling rate, the thinner the wall width of castings is, the bigger the critical pressure increase rate and critical filling rate are; but the figure and the amount of the ingate has no obvious effect on the stationarety of filling. On the basis mentioned above, it is carried out that numeric simulation of filling process of differential-pressure cast and the process design of defferential -pressure cast to some large-scale thin-wall cabin-shape parts, and the result showes that are the smooth and stepwise filling,and the project of differential pressure cast is instituted by the process parameters, which is provide by the hydraulic simulation method. It provides the reference for the produce of this kind of castings. 相似文献