FEM 入门

sillybear

有限元入门程序:
QFEPDE - A Simple Finite Element Program
QFEPDE is a simple finite element program, for a two dimensional spatial domain, with no time dependence, using quadratic elements.
Files you may copy include:
qfepde.f90, the source code.
qfepde.out, sample problem output.
The list of routines includes:
QFEPDE is a simple finite element program
SETINT sets up a Gauss quadrature rule.
GEOM carries out a variety of computations related to the geometry.
ASEM calculates the stiffness matrix and load vector.
QBF evaluates the shape functions and their derivatives.
AA evaluates the coefficient function A(X,Y) in the differential equation.
UEX returns the exact solution of the differential equation.
UEXX returns the X derivative of the exact solution.
UEXY returns the Y derivative of the exact solution.
RHS returns the value of the right hand side of the PDE.
UBC returns the Dirichlet boundary condition at any point on the boundary.
BEPP performs Gauss elimination of a banded linear system.
EROR calculates L2 and H1 errors in the solution.
PRISOL prints the solution as a table of 5 columns.

sillybear

sample problem output

sillybear

看来没人喜欢FEM。我也是。不好理解。

sillybear

要是有人想学的话，我这里有实用的FEM流体程序。

macabre

非常感谢，我需要的，而且是免不了要用的。
非常非常想要，实用的FEM流体程序, 谢谢。
email: wangwang00@21cn.com

山泉

顶

chbo76

算我一个。chbo76@sohu.com

chenweibo

算我一个把，谢谢
chen220322@163.com

kuangtq

sillybear,我是做粘弹流注射成型的数值模拟.要自己编程.给我一份吧,好借鉴借鉴!
先谢过了!
kuangtq@263.net

sunmao2000

这位仁兄的附件很有借鉴价值，特别是对于初学者，
当然，我也是初学者，要搞东fem确实好头痛，找不到好的东西来学，
这位仁兄有关于fem方面的资料，可以给小弟分想一下么？
特别感谢你！！！
联系：sunmao2000@163.com

sillybear

我对FEM不熟，贴几个源代码吗，希望能给想钻研FEM的学友有点帮助。

sillybear

FLOW5 - A Finite Element Code for Fluid Flow
FLOW5 uses the finite element method to solve for the steady state velocity and pressure in a fluid flow region. The fluid is presumed to be incompressible.
Files you may copy include:
flow5.f90, the source code;
cavity.out, the output file;
elements.txt, the element file, suitable for input to the DISPLAY graphics program;
uvp.txt, the UVP file, suitable for input to the DISPLAY graphics program;
flow5.tec, a file suitable for input to the TECPLOT graphics program;
The list of routines includes:
FLOW5 solves a steady state incompressible flow problem using finite elements.
BSP evaluates the linear basis functions for pressure.
DFACT factors a double precision band matrix by elimination.
DSOLVE solves the linear system A*X=B.
FP computes the jacobian matrix A of the Navier Stokes residual.
FX computes the residual RES of the Navier Stokes equations.
INTPRS interpolates the pressure at the midside nodes.
NEWTON applies Newton iteration, seeking a solution of FX(G) = 0.
PLOT writes solution information to two files.
QBF evaluates a nonisoparametric quadratic basis function.
REFBSP evaluates a reference element linear basis function.
REFQBF evaluates a reference element quadratic basis function.
SETBAN computes the lower band width of the Jacobian matrix.
SETBAS evaluates the basis functions at each quadrature point.
SETQUAD sets the abscissas and weights for quadrature in a triangle.
SETNOD assigns numbers to the nodes and elements.
SETXY sets the X and Y coordinates of the nodes.
TRANS calculates the biquadratic reference element transformation.
UVPNORM returns the "norm" of the computed finite element solution.
UVALQ evaluates velocities and pressure at a quadrature point in an element.
VECMAX finds the entry of largest absolute value in a vector.
WRTEC writes out solution information for use with TECPLOT.
XOFXSI computes X and Y given XSI and ETA coordinates.

sillybear

flow5.f90, the source code;
cavity.out, the output file;
elements.txt, the element file, suitable for input to the DISPLAY graphics program;
uvp.txt, the UVP file, suitable for input to the DISPLAY graphics program;
flow5.tec, a file suitable for input to the TECPLOT graphics program;

sillybear

等关注的人多了，我再贴FLOW5的升级版Flow6。
升级版更好，但不一定BUG少。

chbo76

问一下，程序中的有限元单元是三角形单元还是四边形单元？