On the Applicable Ranges of Kinematic and Diffusion Models in Open Channels

by Gye-Woon Choi, Korea Water Resources Corp, Dae Jeon, Republic of Korea,
Geon-Heung Kim, Korea Water Resources Corp, Dae Jeon, Republic of Korea,
Sang-Jin Ahn, Korea Water Resources Corp, Dae Jeon, Republic of Korea,

Document Type: Proceeding Paper

Part of: Hydraulic Engineering


The kinematic and diffusion models using simplified momentum equations of the full dynamic equation have been frequently used for numerical flow simulations, because they have several advantages compared to the full dynamic model. In this paper, the more generally acceptable applicable ranges of kinematic and diffusion models were investigated based on the channel bed slopes So, dimensionless depth increases at upstream boundary Gw and Froude numbers Fr. The applicable ranges were obtained by comparing the relative magnitudes of the terms in the full dynamic equation. In the simulations, a Courant number of 0.5 was used and the channel bed slopes were changed from 0.00001 ft/ft to 0.05 ft/ft. Also, Froude numbers of 0.1, 0.5 and 0.9 were employed. In this paper, it is indicated that the applicable ranges of kinematic models are generally increased with increasing of Froude numbers. However, the applicable ranges of diffusion models are decreased with increasing of Froude numbers. Finally, two figures were proposed as a guideline in the application of kinematic and diffusion models. With applying the proposed criteria, it is expected that the flow simulations in open channels are more efficiently achieved.

Subject Headings: Dynamic models | Kinematics | Diffusion | Hydraulic models | Open channels | Simulation models | Flow (fluid dynamics) | Mathematical models

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