Design Thinking - AguaClara/SWOT GitHub Wiki

In Safe Water on Tap, I remember learning the following steps for design thinking (I listed them in an order that makes sense to me, but the order is fluid since we iterate through them several times):

• Identify success mode
• Find an underlying physics relationship to guide the design
• Identify major constraints/ratios
• Identify failure modes

I remember learning about flocculator design best, so I'll explain each of the steps I listed above in that context. By "Identify success mode" I mean to figure out the main objective and how it can be measured; in the case of the flocculator, the goal is to create flocs and it can be measured by gtheta. I think this step is important to consider before any existing designs are even considered to avoid losing sight of the actual goal and replicating existing designs.

Then, once the objective has been selected, I would look for physics relationships to connect that objective to the design characteristics. I remember a slide of equations that described the relationship between several parameters in the flocculator. I found that visual helpful in that it illustrated how the design isn't based on one guiding equation, but the combination of several.

When it comes to identifying major constraints/ratios, I found it really helpful when you explained why some parameters were fixed, like Gtheta=~37000, and how some ratios between parameters, like the ratio of the distance between expansions to the number of obstacles should be within a certain range. I think it might be a helpful exercise to list out all the parameters that are involved in a design problem, and then everything that is known about each parameter (failure mode, relationships to other parameters, it's role in system performance, optimal value, if it's a material--what sizes is it available in, etc.). I also think it could be helpful to develop some sort of classification system for parameters like "performance," which describe how the system performs (e.g. gtheta, total headloss) or "design decision" and "design decision" variables could be further classified into "fixed", "semi-fixed", or "unconstrained", so that it's more obvious which design decisions need to be made.

Identification of failure modes relates to the identification of major constraints, but in my head it's a separate process. I think pictures you showed in lecture, like the sed tank with a flat bottom that ended up covered in sludge or the baffles that are spaced too close together, were really helpful in forcing us to think about real world implications/practicality of designs because at least for me, I forget about common sense when I'm overly focused on the underlying physics of the process. Another thing on the subject of failure mode that I learned in Safe Water on Tap was the idea of thinking about what happens as a parameter gets very large and very small. I remember having class discussions, where we brainstormed failure modes together, and I think that's a really useful discussion to have.

I definitely still use this type of thinking whenever I'm solving a problem to figure out what I know and what I don't know, so that I can narrow down the problem/solutions to consider. My main takeaway from the class is that constraints can be used as a tool to show you where to direct your mental energy/creativity.

I hope some of that was helpful, and I'm happy to explain anything that was unclear! Also, please let me know if anything I said was incorrect here--I'd be really interested to hear about any ways your approach to design thinking differs.

Nina Blahut Environmental Engineering '21 Cornell University