Reply to the note of Maruyama and Mizushina

Abstract

because the experimental range of Sc by Patel et al. is very narrow (Sc = 3 100 4 050) in view of the scatter of their data. Thus, only the different dependence on Re is admitted from their experiments. This, we infer, is not due to some sources of error suggested by them but rather to their misuse of an input signal as follows.To make (the flow pulsation, Patel et al. change a liquid level in the head tank using an oscillating displacement device immersed in the liquid. They measured the oscillation of the displacement device and tacitly regarded its amplitude and phase as being identical to those of a pressure gradient at test section. In unslteady state, however, the steady state relation between the displacement length of device and 'the pressure gradient does not hold because of dynamic behaviors of fluid in the flow system from the head tank 'to the test section. In particular, the dynamics of fluid in the head tank and through contraction, elbow and two valves largely affect the relation in unsteady state.Hence, the discrepancy in measurements by Patel et al.increased with increasing frequency of pulsation, and it depended on the flow rate, thus on Re.Evidently the dynamic relation between the oscillation of the displacement device and that of the pressure gradient is peculiar to their flow system and is suspected to be too complex to clarify analytically for the use of their study. Accordingly, it is recommended that one avoids this complexity and measures directly the pressure difference or the wall shear stress at the test section as described in the paper of the commentators (Mizushina et a]., 1973). NOTATION 1 L Re = Reynolds number r o Sc = Schmidt number Sn v = kinematic viscosity o = angular frequency Mass Transfer in Laminar Pulsatile Flow in a Tube," AIChE J., 21, 259 (1975). = length of mass transfer section = dimensionless length = 1/ ( 2roReSc) = radius of circular tube = Stokes number = r&o/v Maruyama and Mizushina are quite correct that the work of Mizushina et al. (1973) predates our study of mass transfer in pulsatile laminar flow (Patel et al., 1975). Their data do show excellent correlation with the variableSnScL2f3, which is the variable X I in the notation of our paper.There is no question that direct measurement of the fluctuating pressure difference in the tube is preferable in order to calculate the amplitude ratio and phase lag of the fluctuating transfer coefficient. However, in our work we did not take the amplitude and phase of the displacement device to be identical to those of the pressure gradient in the test section as stated by Maruyama and Mizushina. A dynamic analysis of the flow from the variable head tank through the valves and flow straighteners was done. This analysis yielded a relation between the amplitude and phase of the displacement device and those of the pressure gradient in the tube. Details are given in the thesis by McFeeley (1972). While this procedure is not as accurate as direct measurements of the pressure gradient, the error is not as Iarge as the as...

Reconceiving Reproductive Health Systems: Caring for Trans, Nonbinary, and Gender-Expansive People During Pregnancy and Childbirth

“…64 Some authors have extrapolated from research on cisgender women finding an association between elevated endogenous androgen levels and reduced birth weight, but others have cautioned against relying on data about cisgender women to understand TGE populations who have used testosterone, and existing studies are too small to draw conclusions on this point. 65 Existing research also does not distinguish between individuals who receive appropriate doses of testosterone and those who are inadequately maintained. 66 Finally, there are no reliable data on the incidence of complications such as gestational diabetes or hypertension among TGE people, with or without testosterone use.…”