In a message dated 10/16/01 10:09:23 PM Eastern Daylight Time, tborzic@xxxxxxxxx writes: > Hello everybody, My name is Tomislav and as You may assume > I'm new here and I am looking for some help regarding FEMM. > I am trying to solve some "simple" problem.It goes like this: > 1. Round wire,copper, infinite lenghth,we look at cross section > ,r=0.075m =7.5cm, I= 100 + j0 A,f= 50Hz, relative > permeability is 1.Working with old "pen and paper" i got some results > which are sure correct.Point is to get same thing in FEMM. > What I do is called "numerical callculations of eddy current in round > conductor".I nedd to obtain values of "A" in points r1=0, r2=0.25, > r3=0.5 and r4= 0.75. (In point r4 A = 0, boundary conditon,allready > given). > So what I need is that some one helps me to solve this,tell me > how to define parameters for my problem in FEMM,keeping in mind that I > am new here,but in near future i intend to use FEMM rather often. > My results are: > A1=0.9999951 x10-5 -j0.2109364 x10-7 > A2=0.8888852 x10-5 -j0.1666658 x10-7 > A3=0.5555543 x10-5 -j0.6510389 x10-8 > A4=0.5169879 x10-22 -j0.6638621 x10-19 ( this should be 0 but > this is good enough) > So I need to obtain this rezults with FEMM. > Thanks > This problem is really similar to the example at <A HREF="http://femm.berlios.de/tube/tube.htm";> http://femm.berlios.de/tube/tube.htm</A> Following a similar chain of reasoning to this example, one can show that the solution for tangentially-directed H as a function of radius r is: H = i/(2 Pi R) BesselI[1,a*r]/BesselI[1,a*R] where a=(1+j)/d, and skin depth d is d = Sqrt[1/(Pi*freq*mu_o*sigma)] where freq is the frequency in Hz, mu_o is permeability of free space, and sigma is electrical conductivity. R is the outer radius of the wire, and i is the total current carried by the wire. In my notation, j = Sqrt[-1] and BesselI[1,x] is the modified Bessel function of order 1 of the first kind. I've attached a .fem solution for the same problem. The agreement with the analytical solution is pretty good. > P.S. To mr. David Meeker: > i am translating User's manual to Crotian,for my personal needs,and > for other students on University of Split, who may need it.When I am > done (about 20 days i guess), I can convert it to *.pdf and send it to you > if you want,and make it available for everybody on internet? > > Tomislav Borzic > tborzic@xxxxxxxxx > Great! When you finish it, I'll post it on the web site. Dave -- David Meeker <A HREF="http://members.aol.com/_ht_a/dcm3c";>http://members.aol.com/_ht_a/dcm3c</A> --part1_3e.13021d29.28ff0a16_alt_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: 7bit <HTML><FONT FACE=arial,helvetica><FONT SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0">In a message dated 10/16/01 10:09:23 PM Eastern Daylight Time, tborzic@xxxxxxxxx writes: <BR> <BR> <BR><BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Hello everybody, My name is Tomislav and as You may assume <BR>I'm new here and I am looking for some help regarding FEMM. <BR>I am trying to solve some "simple" problem.It goes like this: <BR>1. Round wire,copper, infinite lenghth,we look at cross section <BR>,r=0.075m =7.5cm, I= 100 + j0 A,f= 50Hz, relative <BR>permeability is 1.Working with old "pen and paper" i got some results <BR>which are sure correct.Point is to get same thing in FEMM. <BR>What I do is called "numerical callculations of eddy current in round <BR>conductor".I nedd to obtain values of "A" in points r1=0, r2=0.25, <BR>r3=0.5 and r4= 0.75. (In point r4 A = 0, boundary conditon,allready <BR>given). <BR>So what I need is that some one helps me to solve this,tell me <BR>how to define parameters for my problem in FEMM,keeping in mind that I <BR>am new here,but in near future i intend to use FEMM rather often. <BR>My results are: <BR>A1=0.9999951 x10-5 -j0.2109364 x10-7 <BR>A2=0.8888852 x10-5 -j0.1666658 x10-7 <BR>A3=0.5555543 x10-5 -j0.6510389 x10-8 <BR>A4=0.5169879 x10-22 -j0.6638621 x10-19 ( this should be 0 but <BR>this is good enough) <BR>So I need to obtain this rezults with FEMM. <BR>Thanks <BR></FONT><FONT COLOR="#000000" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"></BLOCKQUOTE> <BR>This problem is really similar to the example at <A HREF="http://femm.berlios.de/tube/tube.htm";>http://femm.berlios.de/tube/tube.htm</A> Following a similar chain of reasoning to this example, one can show that the solution for tangentially-directed H as a function of radius r is: <BR> <BR></FONT><FONT COLOR="#000000" SIZE=3 FAMILY="SERIF" FACE="Times New Roman" LANG="0">H = i/(2 Pi R) BesselI[1,a*r]/BesselI[1,a*R] <BR> <BR>where a=(1+j)/d, and skin depth d is d = Sqrt[1/(Pi*freq*mu_o*sigma)] where freq is the frequency in Hz, mu_o is permeability of free space, and sigma is electrical conductivity. R is the outer radius of the wire, and i is the total current carried by the wire. In my notation, j = Sqrt[-1] and BesselI[1,x] is the modified Bessel function of order 1 of the first kind.</FONT><FONT COLOR="#000000" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> <BR></FONT><FONT COLOR="#000000" SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> <BR>I've attached a .fem solution for the same problem. The agreement with the analytical solution is pretty good. <BR></FONT><FONT COLOR="#000000" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> <BR></FONT><FONT COLOR="#000000" SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0"><BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">P.S. To mr. David Meeker: <BR>i am translating User's manual to Crotian,for my personal needs,and <BR>for other students on University of Split, who may need it.When I am <BR>done (about 20 days i guess), I can convert it to *.pdf and send it to you <BR>if you want,and make it available for everybody on internet? <BR> <BR>Tomislav Borzic <BR>tborzic@xxxxxxxxx <BR></FONT><FONT COLOR="#000000" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"></BLOCKQUOTE> <BR></FONT><FONT COLOR="#000000" SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> <BR>Great! When you finish it, I'll post it on the web site. <BR> <BR>Dave <BR>-- <BR>David Meeker <BR><A HREF="http://members.aol.com/_ht_a/dcm3c";>http://members.aol.com/_ht_a/dcm3c</A></FONT></HTML> --part1_3e.13021d29.28ff0a16_alt_boundary--
Attachment:
wire.zip
Description: Zip archive