A method of simulating a production process on the basis of a continuous fluid model with discrete time evolution is described. In general, in one aspect, a method for digital image management includes receiving a digital image associated with a specific time. The flexible material may have art, graphics or other indicia applied to the outer exposed side and is easily secured, adjusted and removed on the back of the frame with the use of an adhesive membrane and removable clips. And further comprising a bank of charge storage devices arranged in series and connected across the supply voltage.