C*************************************************************** C Test program for subroutine HMBEMA by Stephen Kirkup C*************************************************************** C C Copyright 2001- Stephen Kirkup C John Tyndall Nuclear Research Institute C School of Computing Engineering and Physical Sciences C University of Central Lancashire - www.uclan.ac.uk C Westlakes Campus C Samuel Lindow Building C West Lakes Science and Technology Park C Whitehaven C Cumbria CA24 3JY C United Kingdom C smkirkup@uclan.ac.uk C C This open source code can be found at C www.boundary-element-method.com/fortran/HMBEMA_T.FOR C C Issued under the GNU General Public License 2007, see gpl.txt C C Part of the the author's open source BEM packages. C All codes and manuals can be downloaded from C www.boundary-element-method.com C C*************************************************************** C C This program is a test for the subroutine HMBEMA. The program computes C the solution to an acoustic/Helmholtz eigenvalue problem interior to C a sphere by interpolating the matrices that arise from the boundary C element method. C C Background C ---------- C C For the eigenvalue problem, the domain lies interior to a closed C boundary S. The boundary condition may be Dirichlet, Robin or C Neumann. For the eigenvalue problem the boundary condidition is C assumed to be homogeneous and have the following general form C C {\alpha}(q) {\phi}(q) + {\beta}(q) v(q) = 0 C C where {\phi}(q) is the velocity potential at the point q on S, v(q) C is the derivative of {\phi} with respect to the outward normal to S C at q and {\alpha}, and {\beta} are complex-valued functions defined C on S. C C Subroutine HMBEMA accepts the range of wavenumbers, the degree of the C interpolating polynomial, a description of the boundary of the domain C and the position of the interior points where the solution ({\phi}) C is sought, the boundary condition and returns the solution ({\phi} C and v) on S and the value of {\phi} at the interior points. C C The test problems C ----------------- C C In this test the domain is a sphere of radius 1 (metre). The acoustic C medium is air (at 20 celcius and 1 atmosphere, c=344.0 (metres per C second), density {\rho}=1.205 (kilograms per cubic metre) and the C solution to the problem with a Dirichlet boundary condition C ({\alpha}=1, {\beta}=0) and with a Neumann boundary condition C ({\alpha}=0, beta=1) are sought. For both problems the frequency is C 400Hz (hence specifying k). C---------------------------------------------------------------------- C The PARAMETER statement C ----------------------- C There are four components in the PARAMETER statement. C integer MAXNS : The limit on the number of boundary elements. C integer MAXNV : The limit on the number of vertices. C integer MAXNK : The limit on the number of interpolation points. C integer MAXNEIG : The limit on the number of eigenvalues (resonant C frequencies) that can be found in the range [KA,KB]. C integer MAXNPI : The limit on the number of interior points. C External modules related in the package C --------------------------------------- C subroutine HMBEMA: Subroutine for solving the Helmholtz eigenvalue C problem (file HMBEMA.FOR contains HMBEMA) C subroutine FNHANK: This computes Hankel functions of the first kind C and of order zero and one. (e.g. file FNHANK.FOR) C subroutine H2LC: Returns the individual discrete Helmholtz integral C operators. (file H2LC.FOR contains H2LC and subordinate routines) C subroutine INTEIG: Finds the eigenvalues of the interpolated matrix C (file INTEIG.FOR contains INTEIG and subordinate routines) C The program PROGRAM HMBEMAT IMPLICIT NONE C VARIABLE DECLARATION C -------------------- C PARAMETERs for storing the limits on the dimension of arrays C Limit on the number of elements INTEGER MAXNS PARAMETER (MAXNS=32) C Limit on the number of vertices (equal to the number of elements) INTEGER MAXNV PARAMETER (MAXNV=MAXNS) C Limit on the number of acoustic frequencies INTEGER MAXNEIG PARAMETER (MAXNEIG=10) C Limit on the number of points interior to the boundary, where C acoustic properties are sought INTEGER MAXNPI PARAMETER (MAXNPI=6) INTEGER MAXNK PARAMETER (MAXNK=4) C Constants C Real scalars: 0, 1, 2, pi REAL*8 ZERO,ONE,TWO,PI C Complex scalars: (0,0), (1,0), (0,1) COMPLEX*16 CZERO,CONE,CIMAG C The reference pressure, used to convert units to decibels. REAL*8 PREREF C Properties of the acoustic medium C The speed of sound [standard unit: metres per second] REAL*8 CVAL C Wavenumber parameter for HMBEMA REAL*8 KA,KB INTEGER NK C Geometrical description of the boundary(ies) C Number of elements and counter INTEGER NS,IS C Number of collocation points (on S) and counter INTEGER NSP,ISP C Number of vetices and counter INTEGER NV,IV C Number of eigenvalues and counter INTEGER NEIG C Index of nodal coordinate for defining boundaries (standard unit is C metres) REAL*8 VERTEX(MAXNV,2) C The two nodes that define each element on the boundaries INTEGER SELV(MAXNS,2) C The points interior to the boundary(ies) where the acoustic C properties are sought and the directional vectors at those points. C [Only necessary if an interior solution is sought.] C Number of interior points and counter INTEGER NPI,IPI C Coordinates of the interior points REAL*8 PINT(MAXNPI,2) C Data structures that are used to define each test problem in turn C and are input parameters to HMBEMA. C SALPHA(j) is assigned the value of {\alpha} at the centre of the C j-th element. COMPLEX*16 SALPHA(MAXNS) C SBETA(j) is assigned the value of {\beta} at the centre of the C j-th element. COMPLEX*16 SBETA(MAXNS) C Validation and control parameters for HMBEMA C Validation switch LOGICAL LVALID C The maximum absolute error in the parameters that describe the C geometry of the boundary. REAL*8 EGEOM C Output from subroutine HMBEMA C The velocity potential (phi - the solution) at the centres of the C elements COMPLEX*16 SPHI(MAXNEIG,MAXNS) C The normal derivative of the velocity potential at the centres of the C elements COMPLEX*16 SVEL(MAXNEIG,MAXNS) C The velocity potential (phi - the solution) at interior points COMPLEX*16 PIPHI(MAXNEIG,MAXNPI) C Workspace for HMBEMA C Working space COMPLEX*16 WKSPC1(MAXNK,MAXNS,MAXNS) COMPLEX*16 WKSPC2(MAXNK,MAXNS,MAXNS) COMPLEX*16 WKSPC3(MAXNK,MAXNS,MAXNS) LOGICAL WKSPC4(MAXNS) REAL*8 WKSPC5(MAXNK) COMPLEX*16 WKSPC6((MAXNK-1)*MAXNS,MAXNS) LOGICAL WKSPC7(MAXNS) COMPLEX*16 WKSP00((MAXNK-1)*MAXNS,(MAXNK-1)*MAXNS) COMPLEX*16 WKSP01((MAXNK-1)*MAXNS,(MAXNK-1)*MAXNS) COMPLEX*16 WKSP02((MAXNK-1)*MAXNS,(MAXNK-1)*MAXNS) REAL*8 WKSP03((MAXNK-1)*MAXNS,(MAXNK-1)*MAXNS) REAL*8 WKSP04((MAXNK-1)*MAXNS,(MAXNK-1)*MAXNS) REAL*8 WKSP05((MAXNK-1)*MAXNS,(MAXNK-1)*MAXNS) REAL*8 WKSP06((MAXNK-1)*MAXNS,(MAXNK-1)*MAXNS) REAL*8 WKSP07((MAXNK-1)*MAXNS) REAL*8 WKSP08((MAXNK-1)*MAXNS) REAL*8 WKSP09(MAXNK) INTEGER WKSP10((MAXNK-1)*MAXNS) COMPLEX*16 WKSP11((MAXNK-1)*MAXNS,(MAXNK-1)*MAXNS) COMPLEX*16 WKSP12((MAXNK-1)*MAXNS) C Counter through the x,y coordinates INTEGER ICOORD C The coordinates of the centres of the elements REAL*8 SELCNT(MAXNS,2) C Other variables REAL*8 EPS COMPLEX*16 EIGVAL(MAXNEIG,MAXNS) C INITIALISATION C -------------- C Set constants ZERO=0.0D0 ONE=1.0D0 TWO=2.0D0 PI=4.0D0*ATAN(ONE) CZERO=CMPLX(ZERO,ZERO) CONE=CMPLX(ONE,ZERO) CIMAG=CMPLX(ZERO,ONE) EPS=1.0E-10 C Reference for decibel scales PREREF=2.0D-05 C Describe the nodes and elements that make up the boundary C :The circle that generates the sphere is divided into NS=18 uniform C : elements. VERTEX and SELV are defined anti-clockwise around the C : boundary so that the normal to the boundary is assumed to be C : outward C :Set up nodes C : Set NS, the number of elements NS=18 C : Set NV, the number of vertices (equal to the number of elements) NV=NS+1 C : Set coordinates of the nodes DATA ((VERTEX(IV,ICOORD),ICOORD=1,2),IV=1,19) * / 0.000D0, 1.000D0, * 0.174D0, 0.985D0, * 0.342D0, 0.940D0, * 0.500D0, 0.866D0, * 0.643D0, 0.766D0, * 0.766D0, 0.643D0, * 0.866D0, 0.500D0, * 0.940D0, 0.342D0, * 0.985D0, 0.174D0, * 1.000D0, 0.000D0, * 0.985D0,-0.174D0, * 0.940D0,-0.342D0, * 0.866D0,-0.500D0, * 0.766D0,-0.643D0, * 0.643D0,-0.766D0, * 0.500D0,-0.866D0, * 0.342D0,-0.940D0, * 0.174D0,-0.985D0, * 0.000D0,-1.000D0 / C :Describe the elements that make up the two boundarys C : Set NS, the number of elements NS=18 C : Set nodal indices that describe the elements of the boundarys. C : The indices refer to the nodes in VERTEX. The order of the C : nodes in SELV dictates that the normal is outward from the C : boundary into the acoustic domain. DATA ((SELV(IS,ICOORD),ICOORD=1,2),IS=1,18) * / 1, 2, * 2, 3, * 3, 4, * 4, 5, * 5, 6, * 6, 7, * 7, 8, * 8, 9, * 9, 10, * 10, 11, * 11, 12, * 12, 13, * 13, 14, * 14, 15, * 15, 16, * 16, 17, * 17, 18, * 18, 19 / C Set the centres of the elements, the collocation points DO IS=1,NS SELCNT(IS,1)=(VERTEX(SELV(IS,1),1) * +VERTEX(SELV(IS,2),1))/TWO SELCNT(IS,2)=(VERTEX(SELV(IS,1),2) * +VERTEX(SELV(IS,2),2))/TWO END DO C Set the points in the acoustic domain where the acoustic properties C are sought, PINT. NPI=4 DATA ((PINT(IPI,ICOORD),ICOORD=1,2),IPI=1,4) * / 0.000D0, 0.000D0, * 0.000D0, 0.500D0, * 0.000D0, -0.500D0, * 0.500D0, 0.000D0 / C The number of points on the boundary is equal to the number of C elements NSP=NS C Open output file OPEN(10,FILE='HMBEMA.OUT',STATUS='UNKNOWN') C TEST PROBLEM 1 C ============== C Properties of the acoustic medium. C the propagation velocity C :Acoustic medium is water at 4 degrees. C [C in metres per second] CVAL=1524.0D0 C :Set nature of the boundary condition by prescribing the values of C the boundary functions SALPHA and SBETA at the collocation points C :In this case a Dirichlet (phi-valued) boundary condition DO 180 ISP=1,NSP SALPHA(ISP)=CONE SBETA(ISP)=CZERO 180 CONTINUE C Search for solutions in the range k in [3,5] KA=3.0D0 KB=5.0D0 C Number of interpolation points (degree+1 of polynomial interpolant) NK=4 C Set up validation and control parameters C :Switch on the validation of HMBEMA LVALID=.TRUE. C :Set EGEOM EGEOM=1.0D-6 CALL HMBEMA(KA,KB,MAXNK,NK, * MAXNEIG, * MAXNV,NV,VERTEX,MAXNS,NS,SELV, * MAXNPI,NPI,PINT, * SALPHA,SBETA, * LVALID,EGEOM, * NEIG,EIGVAL,SPHI,SVEL,PIPHI, * WKSPC1,WKSPC2,WKSPC3,WKSPC4,WKSPC5,WKSPC6,WKSPC7, * WKSP00,WKSP01,WKSP02,WKSP03,WKSP04,WKSP05, * WKSP06,WKSP07,WKSP08,WKSP09,WKSP10,WKSP11,WKSP12) CALL OUTPUT(1,MAXNEIG,NEIG,MAXNPI,NPI,CVAL,PINT, * EIGVAL,PIPHI) C TEST PROBLEM 2 C ============== C Properties of the acoustic medium. C the propagation velocity C :Acoustic medium is water at 4 degrees. C [C in metres per second] CVAL=1524.0D0 C :Set nature of the boundary condition by prescribing the values of C the boundary functions SALPHA and SBETA at the collocation points C :In this case a Dirichlet (phi-valued) boundary condition DO 190 ISP=1,NSP SALPHA(ISP)=CZERO SBETA(ISP)=CONE 190 CONTINUE C Search for solutions in the range k in [40,60] KA=2.0D0 KB=4.0D0 C Number of interpolation points (degree+1 of polynomial interpolant) NK=4 C Set up validation and control parameters C :Switch on the validation of HMBEMA LVALID=.TRUE. C :Set EGEOM EGEOM=1.0D-6 CALL HMBEMA(KA,KB,MAXNK,NK, * MAXNEIG, * MAXNV,NV,VERTEX,MAXNS,NS,SELV, * MAXNPI,NPI,PINT, * SALPHA,SBETA, * LVALID,EGEOM, * NEIG,EIGVAL,SPHI,SVEL,PIPHI, * WKSPC1,WKSPC2,WKSPC3,WKSPC4,WKSPC5,WKSPC6,WKSPC7, * WKSP00,WKSP01,WKSP02,WKSP03,WKSP04,WKSP05, * WKSP06,WKSP07,WKSP08,WKSP09,WKSP10,WKSP11,WKSP12) CALL OUTPUT(2,MAXNEIG,NEIG,MAXNPI,NPI,CVAL,PINT, * EIGVAL,PIPHI) CLOSE(10) END SUBROUTINE OUTPUT(ITEST,MAXNEIG,NEIG,MAXNPI,NPI,CVAL,PINT, * EIGVAL,PIPHI) INTEGER ITEST INTEGER MAXNEIG INTEGER NEIG INTEGER MAXNPI INTEGER NPI REAL*8 CVAL REAL*8 PINT(MAXNPI,2) COMPLEX*16 EIGVAL(MAXNEIG) COMPLEX*16 PIPHI(MAXNEIG,MAXNPI) REAL*8 PI COMPLEX*16 PHIMAX PI=4.0D0*ATAN(1.0D0) DO 100 IEIG=1,NEIG WRITE(10,*) WRITE(10,*) 'TEST PROBLEM ',ITEST WRITE(10,*) 'Resonant wavenumber = ',DBLE(EIGVAL(IEIG)) WRITE(10,*) 'Resonant frequency = ', * DBLE(EIGVAL(IEIG))*CVAL/2.0D0/PI,'Hz' PHIMAX=PIPHI(IEIG,1) DO 130 IPI=2,NPI IF (ABS(PHIMAX).LT.ABS(PIPHI(IEIG,IPI))) * PHIMAX=PIPHI(IEIG,IPI) 130 CONTINUE DO 140 IPI=1,NPI PIPHI(IEIG,IPI)=PIPHI(IEIG,IPI)/PHIMAX 140 CONTINUE WRITE(10,*) ' R Z potential' DO 110 IPI=1,NPI WRITE(10,999) PINT(IPI,1),PINT(IPI,2), * DBLE(PIPHI(IEIG,IPI)),AIMAG(PIPHI(IEIG,IPI)) 110 CONTINUE 100 CONTINUE 999 FORMAT(2F10.4,2F16.8) END