Sir you said that the eqn can be used for free and forced convection bt in the substituting the gradient of pressure in the y direction as hydrostatic pressure u have considered it that external flow is static which not a case of forced convection
Exactly, I have got the same doubt. If you look at the literature, the pressure gradient term is always expressed as a sum of two. One being the hydrostatic pressure gradient and the other being the hydrodynamic pressure gradient. Even in the case of a forced convection over a flat plate (Prandtl's boundary layer equations), the pressure gradient term in the lengthwise direction of the flat plate is considered zero only, because of the geometry of the flat plate. The pressure gradient what we could be missing is the pressure gradient that arises out of the curved body geometry.
At the beginning of the video, Prof said this is actually pressure-driven flow by giving an example p rhoRT relationship but when he wrote gdes, he accepted dp/dx is zero as if flow over a flat plate. Which one is correct or did ı miss some point?
@@rahuljoshi8586 this doesn't answer his question, whether intrinsic or external, it is coming to be 0. And in fact it has to be 0 as system is exposed to atmosphere. In ideal gas equation he just takes P = rhoRT and says Rho more so P more and vice versa. He simply forgot that T is not constant. Ambient T and T near plate are different, then how will P just depend on rho?
pressure difference is the driving force because near the plate where hot air rises due to less density it creates a sort of vacuum over there which is filled by the cold air that is descending and completing the cycle. same as land breeze and sea breeze.
![[CFD] The Boussinesq Approximation for Bouyancy Driven (Natural Convection) Flow](http://i.ytimg.com/vi/onKiVbKSoXw/mqdefault.jpg)
Really clear Thanks!
🙏
Sir you said that the eqn can be used for free and forced convection bt in the substituting the gradient of pressure in the y direction as hydrostatic pressure u have considered it that external flow is static which not a case of forced convection
Exactly, I have got the same doubt. If you look at the literature, the pressure gradient term is always expressed as a sum of two. One being the hydrostatic pressure gradient and the other being the hydrodynamic pressure gradient. Even in the case of a forced convection over a flat plate (Prandtl's boundary layer equations), the pressure gradient term in the lengthwise direction of the flat plate is considered zero only, because of the geometry of the flat plate. The pressure gradient what we could be missing is the pressure gradient that arises out of the curved body geometry.
At the beginning of the video, Prof said this is actually pressure-driven flow by giving an example p rhoRT relationship but when he wrote gdes, he accepted dp/dx is zero as if flow over a flat plate. Which one is correct or did ı miss some point?
It is because he said the pressure is not external but intrinsic.
@@rahuljoshi8586 this doesn't answer his question, whether intrinsic or external, it is coming to be 0. And in fact it has to be 0 as system is exposed to atmosphere. In ideal gas equation he just takes P = rhoRT and says Rho more so P more and vice versa. He simply forgot that T is not constant. Ambient T and T near plate are different, then how will P just depend on rho?
pressure difference is the driving force because near the plate where hot air rises due to less density it creates a sort of vacuum over there which is filled by the cold air that is descending and completing the cycle. same as land breeze and sea breeze.