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Algae biofuels have received attention lately as they can provide a viable alternative to fossil fuels. Algal cells are continuously mixed by a paddle-wheel movement in a large pond, to prevent the settling of algal biomass and increase the productivity. Therefore, the fuel cost is directly proportional to the paddle-wheel energy consumption. The three-dimensional simulation is done to investigate the effect of paddle-wheel rotation on the flow field and dead-zone regions of pond. The results are compared with the case of single phase flow with equivalent momentum source term, which has been used by other researcher in order to optimize pond geometry and estimates the power consumption of paddle-wheel. We observe different flow characteristics in comparison of two cases. When using a source term instead of paddlewheel, the dead zone regions of the pond and flow separation at the hairpin bends are overestimated as a flow depth variation due to centrifugal forces cannot be taken in to account also the depth increase is observed after the paddlewheel, which change the velocity field in entire pond and cannot be modeled by a single-phase flow with the source therm., Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 302-304