This is early stage investigation is related to determination of fresh steel fibre reinforced concrete (SFRC) flow speed gradients, are presumed to be the key parameters for computer modelling of steel fibres orientation in form casting process. The aim of the research is to elaborate the computer model for steel fibre orientation evaluation in the casting process, which would be a good option for prediction the concrete mechanical properties, optimization of casting process and costs due to proper use of ingredients. Fibre orientation in fibre reinforced concrete is important for obtaining best mechanical properties in the place where it’s necessary. Task can be solved as: to obtain optimal fibre concentration and orientation or to use right casting way of concrete with the goal to reach required mechanical properties in necessary location of the composite construction element. As the example were observed the case of trench filling by the fibre concrete. During performed numerical simulations were obtained distributions of vertical and horizontal velocities in real time scale. To confirm the possibility of determining the orientation of fibres by speed gradients in viscous fluid was simulated behaviour of a single fibre in an inclined container with a viscous transparent liquid (potato-starch solution). For precise modelling of potato-starch liquid, coefficient of dynamic viscosity has been determined. The experiments made on the fibres in an inclined container showed satisfactory agreement with the simulation results. Accordingly to calculations the velocity gradients can be used for determine the position and orientation of fibres in fibre-reinforced concrete members production.