[理工] [工數]-PDE
看板Grad-ProbAsk作者fonlintw0621 (fonlintw0621)時間14年前 (2009/10/15 18:56)推噓11(11推 0噓 32→)留言43則, 6人參與討論串7/57 (看更多)
這邊的 d 代表 偏微分
這題在描述 薄膜 軸對稱的 振動
簡單來說 就是 圓柱座標
2 2
d u 1 d u 1 d u
------ + ----- ----- = ---- ------ ( 0 < r < a , t > 0 )
2 2 2
d r r d r c d t
邊界條件
u( 0 , t ) = bounded u ( a , t ) = 0
初始條件
d u
u ( r , 0 ) = f (r) -------- ( r , 0 ) = g ( r )
d t
把一開始的方程式
重新整理
可以得到 兩條 ODE
" 一 條是 bessel "
其中一條 是 2 階 ode
解的過程中 bessel 居多
所以這題 結果這題答案出來是 bessel 的答案
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接下來 是 球體振動
2
1 d 2 d u 1 d u
----- ----- (r ------- ) = ------ ----- ( 0 < r < b ) t > 0
2 d r d r 2 2
r C d t
u (b,t) = 0 u(r,0) = f(r) u ( r , 0 ) = g ( r )
t
這題 PDE 整理之後
也是一樣
可以整理出 兩條 ODE
一條是 也是 bessel
跟 二階 ode
主要是問這題
這兩題是在 喻超凡 下冊 30 頁 跟 37 頁
第一題 可以很順利用 bessel 解出
但是 第二題 我用 bessel 解不出來
有請高手
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我先說 我題目沒打錯喔 = =
整理都會整理出 bessel = =
※ 編輯: fonlintw0621 來自: 114.36.206.56 (10/15 23:03)
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