LR706 East African Flood Model_ Fiddes - Transport for Development
LR706 East African Flood Model_ Fiddes - Transport for Development
LR706 East African Flood Model_ Fiddes - Transport for Development
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In finite difference<br />
<strong>for</strong>m<br />
av<br />
KM= /<br />
VR – VL<br />
2Ax<br />
ay<br />
-/ ax M =<br />
YR – YL<br />
2AX<br />
av<br />
ZP /<br />
=<br />
VP – VM<br />
At<br />
ay<br />
-/ at P =<br />
q=<br />
YP-YM<br />
At<br />
Qin<br />
Ax<br />
Substituting in Equ (1)<br />
YR2 VR – YL2 VL + (YP t YM) (YP - YM)<br />
——.<br />
Qin _ ~<br />
2Ax At mAx -<br />
Simplifying<br />
YP=<br />
. . . 3<br />
From Equ 2<br />
~(vR–vL) + VP–W + +x (YR - YL) = g(So - So<br />
2Ax<br />
At<br />
. . . 4<br />
From the Manning equation<br />
Vp2 n2<br />
sf=—<br />
RP4 /3<br />
and RP =<br />
24X<br />
mYP<br />
where n = Manning’s ‘n”.<br />
Substituting<br />
in (4) and simplifying:<br />
m2@tu–~t#x(VR– VL) t &(YR-YL)–g So=O . ..5<br />
4/3 At At<br />
Equations (3) and (5) are the equations used in the computer program.<br />
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