CFD Analysis of Intake-Structures

CFD Analysis of Intake-Structures

Swirling flows at low-head intakes are a natural phenomenon, but under adverse conditions, intensive swirls may cause air entrainment into the power waterway,

which again can reduce the efficiencies of turbines and pumps and, therefore, it poses the risk of cavitation pitting.

Thus, the optimal intake design of the studied new and unique hydropower scheme needs to balance the risk of vortices with construction costs. In this project, the client decided not to analyze the flow conditions with hydraulic laboratory tests, but to apply CFD techniques.

The present CFD works for the lower and upper Manara reservoirs were conducted in parallel and comprised a stepwise modification of the intake design, based on modelling results and an in-depth-investigation of the vorticity at the optimized layout.

The scope of work included:


  • Complete modelling works to analyse the intake design and to optimize the intake geometry;
  • Qualitative assessment of flow patterns with identification of optimisation potential;
  • Geometry optimisation of side walls and pier nose, including straight and rounded side wall alignment;
  • Identification of reservoir levels with most critical swirling flow conditions and detailed assessment applying refined computational meshes, quantitative criteria and vortex classification.


Based on the present results for the optimized intake design, air entraining vortices are not expected during pump and turbine operation.

Facts to Project

Client: Ellomay Capital Ltd.


  • Computational Fluid Dynamics (CFD) study of flow situation with regards to intake swirl and air intrusion risk
  • Design optimisation of intake structure
  • Detailed analysis of optimised intake design
  • Upper and lower reservoir intakes studied
  • CFD analysis integrated in civil, mechanical and electrical engineering design


Project period: 2018

Location: Israel

Rudolf Faber - Project Manager, Hydro Consulting,  Hydropower
Rudolf Faber
Project Manager, Hydro Consulting, Hydropower

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