CMS-Flow Hydrodnamics: Variable Definitions: Difference between revisions

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The instantaneous current velocity u<sub>i</sub>  is split into:  
The instantaneous current velocity u<sub>i</sub>  is split into:  
Line 9: Line 10:
:<math>\bar{u_i}</math> = current (wave-averaged) velocity [m/s]
:<math>\bar{u_i}</math> = current (wave-averaged) velocity [m/s]


:<math>\tilde{u_i}</math> =  wave (oscillatory) velocity with wave-average <math>\bar{\tilde{u_i}} = 0 [m/s]</math>
:<math>\tilde{u_i}</math> =  wave (oscillatory) velocity [m/s]with wave-average <math>\bar{{u_i}} = 0</math> below the wave trough


:<math>u_i^'</math> = turbulent fluctuation with ensemble average <math>\langle u_i^' \rangle</math> = 0 and wave average <math>\bar{u_i^'}</math> = 0 [m/s]
:<math>u_i^'</math> = turbulent fluctuation [m/s] with ensemble average <math>\langle u_i^' \rangle</math> = 0 and wave average <math>\bar{u_i^'}</math> = 0  


The wave-averaged total volume flux is defined as


The wave-averaged total volume flux is defined as
{{Equation|
{{Equation|
<math>hV_i</math>_ = <math>\bar{{\int_z^\eta} {u_i dz }}</math>
<math> h V_i = \overline{{\int_{z_b}^\eta} {u_i dz }}</math>
|2}}
|2}}


where
where


:<math>h</math> = wave-averaged water depth <math>h=\bar{\eta} - z_b </math> [m]
:<math>h</math> = wave-averaged water depth <math>h=\bar{\eta} - z_b </math> (Figure 1) [m]


:<math>V_i</math> = total mean mass flux velocity or simply total flux velocity for short [m/s]
:<math>V_i</math> = total mean mass flux velocity or simply total flux velocity [m/s]


:<math>u_i</math> = instantaneous current velocity [m/s]
:<math>\eta</math> = instantaneous water level with respect to the Still Water Level (SWL) [m]


:<math>\eta</math> = instantaneous water level with respect to the Still Water Level (SWL) [m]
:<math>\bar{\eta}</math> = wave-averaged water surface elevation with respect to the SWL (Figure 2-1) [m]


:<math>z_b</math>  = bed elevation with respect to the SWL [m]
:<math>z_b</math>  = bed elevation with respect to the SWL (Figure 1) [m]


For simplicity in the notation, the over bar in subsequent wave-averaged variables is omitted.  
<center>
[[File:fig_2_1.png|400px]]


'''Figure 1. Vertical conventions used for the bed and mean water surface elevation.'''
</center>


The total flux velocity is also referred to as the mean transport velocity (Phillips 1977) and mass transport velocity (Mei 1983). The current volume flux is defined as  
The total flux velocity is also referred to as the mean transport velocity (Phillips 1977) and mass transport velocity (Mei 1983). The current volume flux is defined as  
{{Equation|
{{Equation|
<math>hU_i = \int^\eta_{z} \bar{u_i}dz</math>   (2-3)
<math>hU_i = \int^\bar{\eta}_{z_b} \bar{u_i}dz</math>|3}}
|3}}


where <math>U_i</math> is the depth-averaged current velocity. Similarly, the wave volume flux is defined as by  
where <math>U_i</math> is the depth-averaged current velocity. Similarly, the wave volume flux is defined as by  
{{Equation|
{{Equation|
<math>Q_{wi} = hU_{wi} = \bar{\int \tilde{u_i} dz}</math>
<math>Q_{wi} = hU_{wi} = \overline{\int_{\eta_t}^\eta \tilde{u_i} dz}</math>
|4}}
|4}}


where <math>U_{wi}</math> is the depth-averaged wave flux velocity [m/s], and <math>\eta_t</math> = wave trough elevation [m]. Therefore the total flux velocity may be written as  
where  
 
:<math>U_{wi}</math> = depth-averaged wave flux velocity [m/s]
:<math>\eta_t</math> = wave trough elevation [m]
 
 
Therefore the total flux velocity may be written as  
{{Equation|
{{Equation|
<math>V_i = U_i + U_{wi}</math>
<math>V_i = U_i + U_{wi}</math>
|5}}
|5}}
=References=
* Mei, C. 1989. The applied dynamics of ocean surface waves. New York: John Wiley.
* Phillips, O. M. 1977. The dynamics of the upper ocean. (2nd Edition). Cambridge, England: Cambridge University Press.
----
[[CMS#Documentation_Portal | Documentation Portal]]

Latest revision as of 15:26, 18 February 2015


The instantaneous current velocity ui is split into:

 

(1)

in which

= current (wave-averaged) velocity [m/s]
= wave (oscillatory) velocity [m/s]with wave-average below the wave trough
= turbulent fluctuation [m/s] with ensemble average = 0 and wave average = 0

The wave-averaged total volume flux is defined as

 

(2)

where

= wave-averaged water depth (Figure 1) [m]
= total mean mass flux velocity or simply total flux velocity [m/s]
= instantaneous water level with respect to the Still Water Level (SWL) [m]
= wave-averaged water surface elevation with respect to the SWL (Figure 2-1) [m]
= bed elevation with respect to the SWL (Figure 1) [m]

Fig 2 1.png

Figure 1. Vertical conventions used for the bed and mean water surface elevation.

The total flux velocity is also referred to as the mean transport velocity (Phillips 1977) and mass transport velocity (Mei 1983). The current volume flux is defined as

 

(3)

where is the depth-averaged current velocity. Similarly, the wave volume flux is defined as by

 

(4)

where

= depth-averaged wave flux velocity [m/s]
= wave trough elevation [m]


Therefore the total flux velocity may be written as

 

(5)

References

  • Mei, C. 1989. The applied dynamics of ocean surface waves. New York: John Wiley.
  • Phillips, O. M. 1977. The dynamics of the upper ocean. (2nd Edition). Cambridge, England: Cambridge University Press.

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