aqwa中文帮助解析.doc
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1、精选优质文档-倾情为你奉上 ANSYS TO AQWA MODEL TRANSLATORANSYS模型文件转换AQWA-LINE标准输入文件 1. INTRODUCTION 引言 It is possible to use classic ANSYS to create an AQWA radiation/diffraction model. Any of the tools available in Workbench or ANSYS can be used to create the model. Once the model is created an AQWA input file
2、can be written out using a macro supplied with ANSYS. 使用传统的ANSYS产生AQWA辐射/绕射模型是可行的。在Workbench或ANSYS中有工具能够建模。一旦模型建立了,使用ANSYS的宏命令ANSTOAQWA可以自动产生AQWA-LINE的输入文件(将.aqwa修改为.dat格式即可)。2. MODEL DESCRIPTION 模型描述The model must be meshed with the mesh that you wish to use for the AQWA analysis. If you are workin
3、g from a model created for a structural analysis, it will probably be necessary to re-mesh the model as the structural mesh is likely to be finer than is need for a diffraction analysis. 必须使用与AQWA中分析单元类型相同的单元来划分模型的网格。如果你的模型建于ANSYS结构分析,可能会需要不断重新划分网格直到网格尺寸、数目等满足绕射分析的要求。There should be a line of nodes
4、at the waterline, although these nodes do not need to coincide with nodes on the structural model. The translation macro will only make diffracting those elements that are entirely below the waterline. If there are no waterline nodes there will be no diffracting elements at the waterline, which will
5、 severely reduce the accuracy of the diffraction analysis. 吃水线上应该有一行节点,尽管这些节点不需要符合结构模型的节点。转换宏会仅仅将位于吃水线以下的单元制作成绕射单元(DIFF)。如果没有吃水线节点,则吃水线上不会有绕射单元,这会严重的减少绕射分析的准确性。All the panel elements below the water must have their normals pointing outwards. 水下所有的面元必须指示外表面。In AQWA the vertical axis is always the Z-a
6、xis. The translator can convert a model with either Y or Z-axes vertical, but the X-axis must be horizontal and preferably should be along the fore/aft axis of the vessel. 在AQWA中垂向轴总是Z轴。转换器能转换一个以Y或Z为垂直方向的模型,但是X轴必须是水平方向的,最好是沿着船的头/尾轴。If the structure is symmetric and you wish to use the SYMX or SYMY c
7、ards in AQWA, you must only select or of the model as appropriate. If you model a complete vessel and specify X symmetry, the AQWA model will contain two sets of coincident elements.如果结构是对称的,你希望使用AQWA的SYMX或SYMY卡片,你必须仅仅选择1/2或1/4模型。如果你建立一个完整的船模,指定X方向对称,则AQWA模型将会包含2套一致的单元。3. ELEMENT MAPPING 绘制单元The tra
8、nslator maps SHELL41, PLANE42, SHELL43, SHELL63, SHELL181 elements to panels, and PIPE16, PIPE20, PIPE59 elements to TUBEs. It does not recognize any other ANSYS element types. Any material or geometric properties can be used for the shell elements as AQWA does not need any properties at all and the
9、 translator does not use them. 转换器能够绘制SHELL41,PLANE42,SHELL43,SHELL63,SHELL181面单元,及PIPE16,PIPE20,PIPE59管单元。它不识别其他任意的ANSYS单元类型。板壳单元使用的任意材料或几何性质,AQWA都不需要,转换器不会使用这些性质。TUBE elements in AQWA have material density, outside diameter, wall thickness, added mass and drag coefficients, so appropriate properti
10、es should be used in the ANSYS model. PIPE59 elements can have added mass and damping coefficients, and these will be transferred. Note that ANSYS uses the inertia coefficient CM, whereas AQWA uses the added mass coefficient CA, where CM = (1+CA). This correction is made automatically by the transla
11、tor. AQWA管单元具有材料密度,外径,壁厚,附加质量和阻力系数,所以ANSYS建模时应该定义正确的性质。PIPE59单元具有附加质量和阻力系数,这两项会被转换器写入*.DAT文件。注意:ANSYS使用惯性系数,但是AQWA使用附加质量系数,。转换器会自动修正数据。4. RUNNING THE MACRO 运行宏命令When you have created and meshed a model as described above, you can run the macro to generate an AQWA input file. First select the element
12、s that you want to include in the AQWA model. At the command line type “anstoaqwa” optionally followed by a filename. The AQWA input file will be called “file.aqwa”, where file is the name of your database or the filename you have input. You will then be prompted to input a number of parameters in a
13、 window as shown below.当你按照上面的描述建立模型并划分网格后,你能够运行转换宏来产生AQWA输入文件。首先选择你想要包含在AQWA模型中的单元。在命令行上输入ANSTOAQWA命令,后面跟一个文件名。AQWA输入文件会是文件名.aqwa (实际就是.dat文件)。接着你会在弹出的如下窗口中输入一系列的参数。AQWA对网格的要求Rules for Distribution of Diffraction Plate Elements The RULES for the distribution of diffraction pressure plate elements o
14、ver the wetted body surface fall into two categories. These may be classified as rules relating to theoretical considerations and rules relating to numerical computational considerations. The hydrodynamic diffraction/ radiation fluid forces are calculated by using a discrete distribution of fluid SO
15、URCES over the wetted surface of the body (see Section 3.3). These sources are positioned at the centres of the user defined diffraction pressure plate elements. The following rules relate generally to placement and sizing of plate elements which in turn reflects on the distribution of sources. 绕射压力
16、单元在湿表面的分布规则分为两类:考虑理论和数值计算的影响。水动力绕射/入射流体压力是使用整个湿表面上的源离散分布来计算的。这些源定位在用户所定义的绕射压力单元的中心位置。以下的规则主要与压力单元的放置和单元大小有关,反过来会影响源的分布。(A) RULES due to Theoretical Considerations 基于理论考虑的网格规则1 The plate elements, which automatically generate sources, MUST COVER the entire mean wetted surface of the body or bodies. T
17、he body mean wetted surface is that part of the body which is in contact with the fluid when the body is in an equilibrium or steady state position. This wetted surface must be between the fluid free-surface and the sea-bed. 2 The plates, and hence sources, should be CONCENTRATED on those parts of t
18、he body which are likely to experience high fluid flow (e.g. the bow section or aft end section of a ship). 压力单元(或源)必须在浮体可能经受较高流体流动的部分分布密集(例如船尾或弓形部分)3 Plate characteristic dimensions should be LESS THAN 1/7th OF THE INCIDENT WAVE LENGTH. Therefore, the longest side of the plate element should satisf
19、y this criterion. 面元的性能尺寸必须小于突发波高的七分之一,面单元的最长边应该满足这个准则4 Plate element side dimensions should be LESS THAN the local radius of curvature of the surface body part being modelled. This condition cannot be satisfied at sharp corners and these are effectively rounded off (e.g. knuckles on a ships hull).
20、面元边尺寸应该小于表面的局部曲率半径5 Diffracting plates modelling the body surface MUST NOT CUT the free surface of the fluid. Plates below the free surface are allowed by AQWA to be denoted as non-diffracting. 6 Plate element normals MUST point outwards from the body surface into the fluid domain. Plate orientation
21、s should be checked (using AQWA Graphical Supervisor (AGS) as AQWA-LINE cannot detect incorrectly placed plates. 7 If the clearance between the body and the sea-bed is large, and using the wave property of exponential decay with depth, parts of the body at a depth greater than approximately 0.5 the
22、wave length may be ignored in the diffraction/radiation calculation. Note that, when employing this economy tactic, the hydrostatic calculation MUST still be performed over the entire wetted body surface, unless the hydrostatic stiffness matrix is input directly by the user. This hydrostatic informa
23、tion may be acquired from AQWA-LIBRIUM or from other sources (e.g. curves of form). (B) RULES due to Numerical Computational Considerations 1 Element sizes should vary GRADUALLY over the wetted body surface (e.g. larger elements may be used in the parallel mid-body of a ship and gradually decrease i
24、n size as the bow or stern is reached). 单元尺寸应该沿湿表面慢慢变化(例如在平行于船体中间部分使用大尺寸单元,在船尾或船艏使用小尺寸单元)2 Elements should have an aspect ratio of GREATER THAN 1/3. The nearer this is to unity, the better. The aspect ratio of a plate element is defined as follows: 单元应该具有超过1/3的长宽比。这个比值越接近1越好。面元的长宽比定义如下:3 Element cen
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