"question at 4:41 when you guys did the biot number and the characteristic length, you guys just used the radius instead of the radius divide by 3. why could that assumption be made and done?"... I also have the same question as someone below
Especially because @ 5:10, the characteristic length was decided to be R/3 instead of the conservative initial approach. How do you know when to use which one? If you initially used R/3 to solve Bi#, then lumped parameter would have failed and would have needed to use numerical analysis.
question at 4:41 when you guys did the biot number and the characteristic length, you guys just used the radius instead of the radius divide by 3. why could that assumption be made and done?
iAmB2stful The narrator mentioned a 'more conservative method'. I think that by not dividing the radius by 3 the Lc value is therefore larger. This in turn increases the calculated value for the Bi number. By being more conservative and over estimating the Bi number, one can be completely sure that the problem can be solved. Alternatively, if r/3 was used then it would mean that whilst the 'true' Bi number would be found, it doesn't fully indicate that the numbers in the questions are safely and fully in the range in order to be able to use this lumped capacitance method. Basically, by overestimating in engineering you can be 99% sure that it's a valid assumption and calculation
"question at 4:41 when you guys did the biot number and the characteristic length, you guys just used the radius instead of the radius divide by 3. why could that assumption be made and done?"... I also have the same question as someone below
Especially because @ 5:10, the characteristic length was decided to be R/3 instead of the conservative initial approach. How do you know when to use which one? If you initially used R/3 to solve Bi#, then lumped parameter would have failed and would have needed to use numerical analysis.
question at 4:41 when you guys did the biot number and the characteristic length, you guys just used the radius instead of the radius divide by 3. why could that assumption be made and done?
iAmB2stful The narrator mentioned a 'more conservative method'. I think that by not dividing the radius by 3 the Lc value is therefore larger. This in turn increases the calculated value for the Bi number. By being more conservative and over estimating the Bi number, one can be completely sure that the problem can be solved. Alternatively, if r/3 was used then it would mean that whilst the 'true' Bi number would be found, it doesn't fully indicate that the numbers in the questions are safely and fully in the range in order to be able to use this lumped capacitance method. Basically, by overestimating in engineering you can be 99% sure that it's a valid assumption and calculation
Wow!! Great video!