The solar wind interacts with the non-magnetic planet Venus by processes within the mantle region, located between the upstream shock and the ionosphere. In this region exospheric neutral atoms from Venus interact with electrons and ions in the moving plasma and modify its flow, resulting in a region of sharp ion density gradients at the boundary between the ionosphere and the mantle called the ionopause. The effect of mass-loading may be simulated by modifying the mass, momentum, and energy conservation equations to include source and loss terms and electromagnetic forces. Using the assumption that the plasma behaves like a fluid, we construct a model to simplify the physics in the mantle. With this model it is possible to generate an oxygen "ledge" in the ion density similar to the observed ionopause. The calculations also show an enhancement in the magnetic field strength above the ionopause as that observed at Venus.