I was using a very well-known popular computation software direct competitor to ANSYS Multiphysics. I was using it since early version 3 days, through 4.x over

I was using a very well-known popular computation software direct competitor to ANSYS Multiphysics. I was using it since early version 3 days, through 4.x over a period of 3 years in my phd in the field of fluid-structure interaction (e.g. fish in flow). The computations usually took over several days on many cpus for 1 second of real-life simulation, making testing quite painful. Hence, many studies do not involve testing like in software field. I was calculating a parameter enhancement where my calculations were showing a great 180% enhancement; this result would make it into very high ranking (15+ IF) paper right away. By then, several people had written numerous papers on this matter using this multiphysics software in well-known journals. But my gut feeling didn't let me. Eventhough my professors were pressing me to publish, I took 6 painful months (toward the end of my phd) to rigorously test the software itself, having nothing to do with my work, since it was closed-source. After 6 months, I found out that a velocity term used in their stabilization algorithm does not use relative velocity, but absolute velocity, leading to enormous amount of fake diffusion into the model. I had to travel to another city in europe to convince them that there is such bug. Every single work in my field that used this software till then had been severely invalid. And what the developers did: they fixed the bug in the next sub-release without putting it in the changelog like nothing happened.