Morimoto:Shape was paramount. Our main challenge was streamlining the contours to reduce drag from swimming as much as possible, but there was no precedent for submersible products at Sony, and there's a limit to how well you can design things by relying on conjecture and subjective field test values. That's why, on Fukuma's suggestion, we enlisted the support of a department at Sony specializing in computer-aided engineering (CAE). It was a design challenge we had never faced before.
Fukuma:Independently and with others, Sony has developed an approach to product styling and performance that leverages the power of computer simulations. We call this algorithmic design. To understand underwater performance for the new W series, we worked with a CAE department at Sony experienced in fluid dynamics analysis. We conducted many simulations to see how much drag the current model and Morimoto's proposed shapes produced underwater. To make the results more tangible for our design team, I requested not only numerical and verbal descriptions of the outcomes but also visual representations, in still images and animated sequences. Presented visually, the areas of maximum drag were clear for anyone to see. The CAE department's contributions enabled us to share this information in easy-to-understand formats, so that we could apply the analysis data intuitively and refine the design.
Narrowing down the optimal shape through recursive fluid dynamics analysis
Morimoto:Our simulations showed that with previous shapes (which had rounded ends), water tended to get between the headphones and the user's face, making it easier for the headphones to come off. To have water push the headphones toward your face instead of away from it, we reduced the inner roundness as much as possible and enlarged the outer curvature. This effect of drag was one detail we would not have noticed without running simulations.
Fukuma:The direction of water resistance changes a lot as you take each breath while swimming. To make sure we were reducing this resistance from all angles, we tested the shape in 3D simulations at the moment of maximum drag in freestyle swimming. In a consumer electronics project, it was a rare and valuable instance of close collaboration between design and CAE departments, as insight from simulations was directly applied to refine the shape. In the end, we succeeded in reducing the force of water pulling the headphones away to about one-third of the previous model (NWD-W263). Design based only on impressions from field tests is not persuasive enough, and design based only on simulations tends to be too theoretical. This time, we took the best insight from both perspectives to perfect the first WALKMAN® you can swim with.
Toward a more compact player, with an optimal center of gravity
Morimoto:As we refined the shape through repeated simulations, we also studied the shapes of orcas and other marine animals, as we considered what the shape should remind people of. We sought a synergy from both viewpoints, and this yielded an effective shape that also looks stylish. The resulting shape is composed of graceful, organic curves, although they are not easy to produce in manufacturing.
Morimoto:We also paid careful attention to the design of the charger. Only one end has the charging interface, so we did explore a charger only attached by that end, but it was hardly elegant, with the other end dangling free. We decided that the player should also look its best when it's just sitting there, so the charger holds both ends securely. This also makes it easier to pick it up after charging.
A special carrying case is also available for this W series model. Here, a highlight is the zipper, which creates a waterproof seal. You'll probably dry them off after swimming, but any water still on them would get your bag wet if you tossed them inside. That's why the zipper is a nice touch, because it keeps any moisture away from your bag. These are the kinds of WALKMAN® scenarios we imagine during design.