TUFLOW 2D Hydraulic Structures: Difference between revisions
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= 2D Bridge Modelling in TUFLOW - Overview =
The TUFLOW 2D solution explicitly predicts the majority of “macro” losses due to the expansion and contraction of water through a constriction, or around a bend, provided the resolution of the grid is sufficiently fine (<u>[
==Contraction/Expansion Losses (“Macro” Losses)==
Loss of energy is caused by the flow contraction during the expansion of water after the vena-contracta inside a bridge section and the flow expansion downstream a bridge. As discussed above, this type of "macro" losses can be explicitly resolved by the TUFLOW 2D solver, provided that a proper turbulence model and mesh size are used. Below is an example of the 2D modelling of flow contraction/expansion at a pair of bridge abutments.
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This table can be used to estimate the deck form loss coefficient based on the bridge design (hB/T). The solid portion of the guard rails (blockage * rail depth) can be added to T in addition to the deck thickness to calculate hB/T. For bridge with more complicated designs (e.g. girders), higher form loss might be required due to the higher surface roughness of the bridge.
'''NOTE''': This form loss value should not be confused with the value of 1.56 used in the pressure flow approached adopted in <u>[[1D_Bridges | TUFLOW 1D "B" and "BB" bridge]]</u>. TUFLOW 1D bridge pressure flow approach is based on the section 4.13.2 "All Girders in Contact with Flow (Case II)" of ''Guide to Bridge Technology Part 8: Hydraulic Design of Waterway Structures'' (AUSTROADS, 2019). The original hydraulic experiment conducted by <u>[
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