The increasing demand for components with tailored properties and functionally graded materials featuring adjustable interfaces is raising the requirements in gravity sand and die casting processes of aluminium. In response to these challenges, a novel controlled process based on injector casting is being developed. This innovative process involves the sequential pouring of two liquid aluminium alloys into a mould while mixing the two liquid phases. By adjusting the injector outlet, the process aims to achieve a horizontal flow deflection. This study systematically investigates two variations of horizontal deflections at the injector outlet and examines their impacts on flow volume rate, flow velocity, and the flow channel at the injector outlet in relation to their impact on the mixing characteristics. These variations are analysed through water model experiments. The findings from these water model experiments are critically evaluated to assess their applicability to the aluminium casting process. Based on these evaluations, conclusions are drawn to improve the design of an application-specific injector for a multi-material injector casting process (MMIC). The results offer valuable insights into optimising the manufacturing process to achieve the desired material properties and gradient configurations.