This dataset contains the results of a parametric mesh study to quantify the discretization uncertainty of steady state multi-reference frame simulations on a counter rotating pico-hydraulic turbine reference case [1][2]. The results of this study were used in the published article [3] for numerical validation purposes. The mesh was made with open-source tool Salome-Platform for the bulk domains and Ansys Turbogrid�� for the blade row domains. The simulations where made with OpenFoamV8 open-source library. Three meshes where evaluated, taking in account an effective size ratio r=1.4 (eq. 1). The results where analyzed using the Roache's convergence index, obtaining for the medium mesh about 2% of discretization uncertainty on the total power, and less than 1% on pressure head. \( r = \left(\frac{N_\mathrm{fine}}{N_\mathrm{medium}}\right)^\frac{1}{3} = \left(\frac{N_\mathrm{medium}}{N_\mathrm{coarse}}\right)^\frac{1}{3} \) (1) Additional simulations where made with the medium mesh to reconstruct the hydraulic efficiency curve. Main simulation results folders: picoTurbineValCase/sim/results/MS[0-2] contains the mesh study simulation results picoTurbineValCase/sim/results/curve contains the off-design simulation results On the meshStudy.org file a summary of the calculations is given. [1] T. SHIGEMITSU, Y. TAKESHIMA, Y. OGAWA, J. FUKUTOMI, Internal flow of contra-rotating small hydroturbine at off- design flow rates, IOP Conference Series: Earth and Environmental Science 49 (2016) 102008. doi:10.1088/1755-1315/49/10/102008. [2] T. Shigemitsu, T. Ikebuchi, D. Nan, T. Hosotani, Performance im provement of contra-rotating small hydroturbine, in: Renewable Energy and Sustainable Buildings, Springer International Publishing, 2019, pp. 313���325. doi:10.1007/978-3-030-18488-9_24. [3] Abraham Vivas, A. Viedma & A. S. Kaiser. (2021). In-pipe axial pico-hydraulic tailored turbine design: A novel approach using a dimensionless design chart. Energy Conversion and Management, 250, p.114884. https://doi.org/10.1016/j.enconman.2021.114884