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| <div class="title">Suspended Sediment Test in Channel</div> | | <div class="title">Suspended Sediment Test in Channel</div> |
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| This case provides a fundamental check of the ability of a model to 1) represent a simple flow, 2) flux material from the bed, and 3) develop a suspended-sediment profile.
| | The previous contents of this page have been move to their proper location: [[TEST_CHAN_CASE]]. |
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| This case provides a fundamental check of the ability of a model to 1) represent a simple flow, 2) flux material from the bed, and 3) develop a suspended-sediment profile.
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| [[Image:Test_case_1.gif|center]] | |
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| '''Model Parameters'''
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| The following parameters were used for the Suspended Sediment Test in Channel test case.
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| {| border = "1"
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| !Model Parameter
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| !Variable
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| !Value
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| |-
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| |length, width, depth
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| |Xsize, Esize, depth
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| |align="left"|10000 m, 100 m, 10 m
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| |-
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| |number of grid spacings
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| |Lm, Mm, Nm
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| |align="left"|100, 10, 20 (+variable)
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| |-
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| |bottom roughness
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| |Zob
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| |align="left"|0.0053 m
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| |-
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| |time step
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| |dt
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| |align="left"|30 s
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| |-
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| |simulation steps
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| |Ntimes
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| |align="left"|5000
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| |-
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| |settle velocity
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| |ws
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| |align="left"|1.0 mm s-1
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| |-
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| |erosion rate
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| |E0
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| |align="left"|5x10-5 kg m-2 s-1
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| |-
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| |critical stresses
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| |τce
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| |align="left"|0.05 N m-2
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| |-
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| |porosity
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| |ϕ
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| |align="left"|0.90
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| |-
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| |bed slope
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| |S0
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| |align="left"|4x10-5
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| |-
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| |Inflow/Outflow boundary condition
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| |u
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| |align="left"|1 m s-1
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| |}
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| '''Channel Initial Conditions'''
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| Channel initial conditions:
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| The test channel was modeled by establishing a grid parameterized with dx = 100 m , dy=100 m, f0 = 0, and h = 10 m (flat bottom). Initial conditions set a vertical logarithmic velocity profile for u (not required but provided reasonable starting values), v = 0, zeta (water surface height) = 0, SSC in the water column = 0, and bed thickness = 1 m (to provide unlimited supply). The model was forced with 2 methods :
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| —Simulation 1: Imposing a constant flow of 10 m³/s/m of width. This simulation allowed that water surface elevation to vary. Radiation boundary conditions were imposed for the water level along with a constant flow imposed by a depth averaged velocity ubar = 1.0 m/s at the upstream and downstream boundaries.
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| —Simulation 2: Imposing a constant bed slope and water surface slope of 4x10-5 m/m. This simulation forced the water surface elevation and hence the bottom stress. Radiation boundary conditions were imposed for the depth-averaged velocity along with a clamped water surface condition at each boundary. The bed slope of 4x10-5 was selected to produce a depth-averaged velocity of 1m/s (similar to simulation 1) with a Z0 = 0.005.
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| For both simulations, vertical mixing was parameterized using six different closure schemes: MY25, KKLpara, KKLmin, KE, KW88, and ANA
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| MY25 = Mellor Yamada Level 2.5 Closure, parabolic wall proximity function
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| KKLpara = Generic Length Scale parameterized as Mellor Yamada Level 2.5 with a parabolic wall proximity function
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| KKLmin = Generic Length Scale parameterized as Mellor Yamada Level 2.5 with a linear wall proximity function (minimum distance to each surface)
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| KE = Generic Length Scale parameterized as k-epsilon closure
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| KW88 = Generic Length Scale parameterized as k-omega closure
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| ANA = analytical expression of a parabolic vertical eddy diffusivity and viscosity profile:
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| Kz = k u* z (1 - z/D)
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| where Kz = vertical eddy viscosity, m²/s
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| z = height above the bottom, m
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| D = depth of flow, m, = 10 m
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| and u* = friction velocity which was calculated according to the logarithmic profile.
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Suspended Sediment Test in Channel
The previous contents of this page have been move to their proper location: TEST_CHAN_CASE.
