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__NOTOC__
==Experiment Setup==
The laboratory flume experiment of Rajaratnam and Nwachukwu (1983) consists of a rectangular 37 x 0.92 m flume with open-channel flow and a thin plate of length 0.1524 m used to simulate a groin-like structure. Here the numerical model is compared to experiment A1 of Rajaratnam and Nwachukwu (1983). For this case, the flow depth and discharge were 0.189 m and 0.0453 m<sup>3</sup>/sec, respectively.
==Model Setup==
The computational grid size is 152 x 36 and has a variable grid resolution of 0.01 to 0.05 m (Figure 1). The mesh was refined manually near the structure, near the walls within the recirculation zone behind the structure. A constant flux was specified at the inflow boundary and a zero water level at the outflow boundary.
[[Image:SpureDikeGrid2.png|thumb|none|1000px|Figure 1. Computational  grid for experiment A1 of Rajaratnam and Nwachukwu (1983) .]]
<br style="clear:both" />


==Results==
Flow velocities were measured down stream of the flow structure along 4 transects in the transverse direction and at two arbitrary levels or heights y/y0=0.03 and y/y0=0.85. The velocities from y/y0=0.85 are compared to the calculated depth-averaged velocities and are shown in Figure 2.


[[Image:SpureDike_Transects_10k.png|thumb|none|600px|Figure 2.  Comparison of measured and computed transect]]
<br style="clear:both" />


[[Image:SpureDike_Waterlevel_Current_10k.png|thumb|none|1000px|Figure 3.Computed water levels and currents]]


 
<br style="clear:both" />
<font size = "4">'''Experiment Setup'''</font>
'''Table 1. Goodness of fit statistics for U-velocity, m/s'''
The laboratory flume experiment of Rajaratnam and Nwachukwu (1983) consists of a rectangular 37 x 0.92 m flume with open-channel flow and a thin plate of length 0.1524 m used to simulate a groin-like structure. Here the numerical model is compared to experiment A1 of Rajaratnam and Nwachukwu (1983). For this case, the flow depth and discharge were 0.189 m and 0.0453 m<sup>3</sup>/sec, respectively.
'''Model Setup'''
The computational grid size is 152 x 36 and has a variable grid resolution of 0.01 to 0.05 m (Figure 1). The mesh was refined manually near the structure, near the walls within the recirculation zone behind the structure. A constant flux was specified at the inflow boundary and a zero water level at the outflow boundary.
{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;"
|Outlet, given Pressure  BC<br>
|}
[[Image:Spure_Dike_01.gif]]
{|border="2" cellspacing="0" cellpadding="4" width="100%"
|
{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;"
|Grid A<br>
|}
[[Image:Spure_Dike_12.gif]]
{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;"
|a.<br>
|}
[[Image:Spure_Dike_10.gif]]
[[Image:Spure_Dike_02.gif]]
[[Image:Spure_Dike_05.gif]]
{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;"
|Outlet, given WSE  BC<br>
|}
[[Image:Spure_Dike_03.gif]]
{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;"
|Inlet, Flux  BC<br>
|}
[[Image:Spure_Dike_04.gif]]
[[Image:Spure_Dike_14.png|framed|none]]
|-
|
{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;"
|Grid B<br>
|}
[[Image:Spure_Dike_13.gif]]
{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;"
|b.<br>
|}
[[Image:Spure_Dike_11.gif]]
{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;"
|Outlet, given WSE BC<br>
|}
[[Image:Spure_Dike_09.gif]]
[[Image:Spure_Dike_08.gif]]
[[Image:Spure_Dike_07.gif]]
{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;"
|Inlet, Flux BC<br>
|}
[[Image:Spure_Dike_06.gif]]
[[Image:Spure_Dike_15.png|framed|none]]
|}
Figure 1. Computational grids used in experiment A1.
'''Results'''
Flow velocities were measured down stream of the flow structure along 4 transects in the transverse direction and at two arbitrary levels or heights
[[Image:Spure_Dike_16.png|framed|none]]
=0.03 and
[[Image:Spure_Dike_17.png|framed|none]]
=0.85. The velocities from
[[Image:Spure_Dike_18.png|framed|none]]
=0.85 are compared to the calculated depth-averaged velocities and are shown in Figure 2.
Table 1. Goodness of fit statistics for U-velocity, m/s
{|border="2" cellspacing="0" cellpadding="4" width="79%"
{|border="2" cellspacing="0" cellpadding="4" width="79%"
|&nbsp;
|&nbsp;
|Transect 1
|'''Transect 1''' || '''Transect 2''' || '''Transect 3''' || '''Transect 4'''
|Transect 2
|Transect 3
|Transect 4
|-
|-
|RMSE
|RMSE || 0.0504 || 0.0690 || 0.0557 || 0.0627
|0.0504
|0.0690
|0.0557
|0.0627
|-
|-
|RMAE
|RMAE || 0.0239 || 0.0725 || 0.0884 || 0.1038
|0.0239
|0.0725
|0.0884
|0.1038
|-
|-
|R<sup>2</sup>
|R<sup>2</sup> ||0.978 || 0.951 || 0.975 ||0.993
|0.978
| 0.951
| 0.975
| 0.993
|}
|}
* For a definition of the goodness of fit statistics see [[Statistics |  Goodness of fit statistics]].
<br style="clear:both" />
==References==
*Rajaratnam, N. and Nwachukwu, B.A. (1983). "Flow near groin-like structures." ''Journal of Hydraulic Engineering'', 109(3),  463-480.
   
   
'''Results and Discussion'''
----
----
'''References'''
[[Test_Cases | Test Cases]]
 
Rajaratnam,N. and Nwachukwu, B.A. (1983). "Flow near groin-like structures." ''J. Hydraulic Eng.'', 109(3),  463-480.
[[CMS#Documentation_Portal  | Documentation Portal]]
[[category:uncategorized]]

Latest revision as of 17:31, 1 June 2011

Experiment Setup

The laboratory flume experiment of Rajaratnam and Nwachukwu (1983) consists of a rectangular 37 x 0.92 m flume with open-channel flow and a thin plate of length 0.1524 m used to simulate a groin-like structure. Here the numerical model is compared to experiment A1 of Rajaratnam and Nwachukwu (1983). For this case, the flow depth and discharge were 0.189 m and 0.0453 m3/sec, respectively.

Model Setup

The computational grid size is 152 x 36 and has a variable grid resolution of 0.01 to 0.05 m (Figure 1). The mesh was refined manually near the structure, near the walls within the recirculation zone behind the structure. A constant flux was specified at the inflow boundary and a zero water level at the outflow boundary.

Figure 1. Computational grid for experiment A1 of Rajaratnam and Nwachukwu (1983) .


Results

Flow velocities were measured down stream of the flow structure along 4 transects in the transverse direction and at two arbitrary levels or heights y/y0=0.03 and y/y0=0.85. The velocities from y/y0=0.85 are compared to the calculated depth-averaged velocities and are shown in Figure 2.

Figure 2. Comparison of measured and computed transect


Figure 3.Computed water levels and currents


Table 1. Goodness of fit statistics for U-velocity, m/s

  Transect 1 Transect 2 Transect 3 Transect 4
RMSE 0.0504 0.0690 0.0557 0.0627
RMAE 0.0239 0.0725 0.0884 0.1038
R2 0.978 0.951 0.975 0.993


References

  • Rajaratnam, N. and Nwachukwu, B.A. (1983). "Flow near groin-like structures." Journal of Hydraulic Engineering, 109(3), 463-480.

Test Cases

Documentation Portal

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