Download - NAVIER STOKES EQ - Högskoleingenjörsutbildningingforum.haninge.kth.se/.../HL2008/NAVIER_STOKES_EQ.pdfNavier - Stokes equation: We consider an incompressible , isothermal Newtonian

Transcript

Navier - Stokes equation:

We consider an incompressible , isothermal Newtonian flow (density ρ =const, viscosity μ =const), with a velocity field ))()()(( x,y,z, w x,y,z, vx,y,zuV =

r

Incompressible continuity equation:

0=∂∂

+∂∂

+∂∂

zw

yv

xu eq1.

Navier - Stokes equation:

vector form: VgPDt

VD rrr

2∇++−∇= μρρ

x component:

)( 2

2

2

2

2

2

zu

yu

xug

xP

zuw

yuv

xuu

tu

x ∂∂

+∂∂

+∂∂

++∂∂

−=⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

+∂∂

+∂∂

+∂∂ μρρ eq2.

y component:

)( 2

2

2

2

2

2

zv

yv

xvg

yP

zvw

yvv

xvu

tv

y ∂∂

+∂∂

+∂∂

++∂∂

−=⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

+∂∂

+∂∂

+∂∂ μρρ eq3.

z component:

)( 2

2

2

2

2

2

zw

yw

xwg

zP

zww

ywv

xwu

tw

z ∂∂

+∂∂

+∂∂

++∂∂

−=⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

+∂∂

+∂∂

+∂∂ μρρ eq4.

Cylindrical coordinates ),,( zr θ : We consider an incompressible , isothermal Newtonian flow (density ρ =const, viscosity μ =const), with a velocity field .uuuV zr ),,( θ=

r

Incompressible continuity equation:

0)(1)(1

=∂∂

+∂

∂+

∂∂

zuu

rrru

rzr

θθ eq a)

r-component:

⎥⎦

⎤⎢⎣

⎡∂∂

+∂∂

−∂∂

+−⎟⎠⎞

⎜⎝⎛

∂∂

∂∂

++∂∂

−=

⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

+−∂∂

+∂∂

+∂∂

2

2

22

2

22

2

211zuu

ru

rru

rur

rrg

rP

zuu

ruu

ru

ruu

tu

rrrrr

rz

rrr

r

θθμρ

θρ

θ

θθ

eq b)

θ -component:

⎥⎦

⎤⎢⎣

⎡∂∂

+∂∂

+∂∂

+−⎟⎠⎞

⎜⎝⎛

∂∂

∂∂

++∂∂

−=

⎟⎠⎞

⎜⎝⎛

∂∂

++∂∂

+∂∂

+∂∂

2

2

22

2

22

2111zuu

ru

rru

ru

rrr

gPr

zu

uruuu

ru

ru

ut

u

r

zr

r

θθθθθ

θθθθθθ

θθμρ

θ

θρ

eq c)

z-component:

⎥⎦

⎤⎢⎣

⎡∂∂

+∂∂

+⎟⎠⎞

⎜⎝⎛

∂∂

∂∂

++∂∂

−=

⎟⎠⎞

⎜⎝⎛

∂∂

+∂∂

+∂∂

+∂∂

2

2

2

2

2

11zuu

rrur

rrg

zP

zuuu

ru

ruu

tu

zzzz

zz

zzr

z

θμρ

θρ θ

eq d)