Biomedical Engineering Blood Pressure / Blood Flow
Biomedical Engineering Blood Pressure / Blood Flow
Biomedical Engineering Blood Pressure / Blood Flow
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RUPRECHT-KARLS-<br />
UNIVERSITY HEIDELBERG<br />
Computer Assisted Clinical Medicine<br />
Patrick Heiler<br />
11/25/2011 | Page 11 Fluids in Motion I<br />
FF<br />
dv<br />
=η ⋅ A<br />
dr<br />
η ... viscosity<br />
F r<br />
⎡ NS ⎤<br />
⎢ 2 ⎥<br />
⎣ m ⎦<br />
v(r)<br />
A<br />
liquid<br />
Examples:<br />
fluid<br />
water<br />
blood<br />
glycerin<br />
mercury<br />
η [mNs/m 2 ]=[mPas]<br />
1.002<br />
approx. 3-5<br />
1480<br />
1.55<br />
T = 20°<br />
RUPRECHT-KARLS-<br />
UNIVERSITY HEIDELBERG<br />
Computer Assisted Clinical Medicine<br />
Patrick Heiler<br />
11/25/2011 | Page 12 Fluids in Motion II<br />
laminar current:<br />
frictional force > accelerating Force<br />
otherwise formation of turbulences possible (where velocity gradient is strong)<br />
distinction: Reynolds number:<br />
Re =<br />
ρ ⋅v ⋅ D<br />
η<br />
D ... characteristic length<br />
... tube diameter<br />
• laminar flow: Re < 2300<br />
• transient: 2300 < Re < 4000<br />
• turbulent flow: Re > 4000<br />
Seite 6<br />
6
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