Wall shear stresses are widely accepted as the primary influence affecting characteristics of anchored cells subjected to fluid flow. For example, endothelial cells lining the interior walls of arteries and veins experience shear exerted by the flow of blood and become aligned and elongated with the direction of flow and undergo other physiological and biochemical changes. The realization of the relationship between hemodynamic forces on the endothelium and the origins of atherosclerosis and vascular pathology, in general, has led to considerable attention focusing on the effects of these forces on cellular responses. Detailed, accurate information about the fluid forces acting on cells must be known in order to understand the cause and effect relationship between shear stresses and endothelial responses. A computational model that defines complete spatial and temporal resolution of shear on cells cultured in rotary orbital shakers is presented here. Computational methods are employed that simulate flow in cell culture dishes that rotate on commonly used orbital shaker platforms. This computational model allows for the determination of wall shear stresses over the entire area of the bottom surface of a dish (representing the growth surface for anchorage dependent cells in culture) which was previously too complex for accurate quantitative analysis. Results provide shear values that are oscillatory in nature and not steady as has previously been assumed due to quantitative and experimental limitations. The model is validated with experimental data obtained at discreet locations on a dish surface. Knowledge of complete spatial and temporal resolution inside an orbiting culture dish will significantly enhance the usefulness of simple shaker apparatuses in the study of cellular responses to fluid forces.