In this paper, we modify the convective vorticity vector (CVV) defined as a cross product of absolute vorticity and gradient of equivalent potential temperature to moist potential vorticity vector (MPVV) defined as a ...In this paper, we modify the convective vorticity vector (CVV) defined as a cross product of absolute vorticity and gradient of equivalent potential temperature to moist potential vorticity vector (MPVV) defined as a cross product of absolute vorticity () and the gradient of the moist-air entropy potential temperature (). The patterns of (MPVV) are compared with the patterns of heavy rainfall events that occurred over different regions in Tanzania on 20<sup>th</sup> to 22<sup>nd</sup> December, 2011 and on 5<sup>th</sup> to 8<sup>th</sup> May, 2015. Moreover, the article aimed at assessing the relative contributions of the magnitude, horizontal and vertical components of (MPVV) detecting on the observed patterns of rainfall events. Dynamic and thermodynamic variables: wind speed, temperature, atmospheric pressure and relative humidity from numerical output generated by the Weather Research and Forecasting (WRF) model running at Tanzania Meteorological Agency (TMA) were used to compute MPVV. It is found that MPVV provide accurate tracking of locations received heavy rainfall, suggesting its potential use as a dynamic tracer for heavy rainfall events in Tanzania. Finally it is found that the first and second components of MPVV contribute almost equally in tracing locations received heavy rainfall events. The magnitude of MPVV described the locations received heavy rainfall events better than the components.展开更多
In all convective heat transfer situations, losses occur in the flow field （by dissipation） as well as in the temperature field （by conduction）. Typically these losses are more or less quantified by the friction f...In all convective heat transfer situations, losses occur in the flow field （by dissipation） as well as in the temperature field （by conduction）. Typically these losses are more or less quantified by the friction factorfwith respect to losses in the flow field, and the Nusselt number Nu for the heat transfer quality. Assessing the process of convective heat transfer as a whole, then becomes problematic because two different non-dimensional quantities, f and Nu, have to be combined somehow. From a thermodynamics point of view, there is a reasonable alternative： Since all losses become manifest in corresponding entropy generation rates, these rates are determined in the velocity as well as in the temperature field. Based on the integration of the entropy generation fields, an energy devaluation number is introduced. It basically determines how much oftbe so-called entropic potential of the energy involved in a convective heat transfer process is used within it. This approach is called SLA （second law analysis）.展开更多
文摘In this paper, we modify the convective vorticity vector (CVV) defined as a cross product of absolute vorticity and gradient of equivalent potential temperature to moist potential vorticity vector (MPVV) defined as a cross product of absolute vorticity () and the gradient of the moist-air entropy potential temperature (). The patterns of (MPVV) are compared with the patterns of heavy rainfall events that occurred over different regions in Tanzania on 20<sup>th</sup> to 22<sup>nd</sup> December, 2011 and on 5<sup>th</sup> to 8<sup>th</sup> May, 2015. Moreover, the article aimed at assessing the relative contributions of the magnitude, horizontal and vertical components of (MPVV) detecting on the observed patterns of rainfall events. Dynamic and thermodynamic variables: wind speed, temperature, atmospheric pressure and relative humidity from numerical output generated by the Weather Research and Forecasting (WRF) model running at Tanzania Meteorological Agency (TMA) were used to compute MPVV. It is found that MPVV provide accurate tracking of locations received heavy rainfall, suggesting its potential use as a dynamic tracer for heavy rainfall events in Tanzania. Finally it is found that the first and second components of MPVV contribute almost equally in tracing locations received heavy rainfall events. The magnitude of MPVV described the locations received heavy rainfall events better than the components.
文摘In all convective heat transfer situations, losses occur in the flow field （by dissipation） as well as in the temperature field （by conduction）. Typically these losses are more or less quantified by the friction factorfwith respect to losses in the flow field, and the Nusselt number Nu for the heat transfer quality. Assessing the process of convective heat transfer as a whole, then becomes problematic because two different non-dimensional quantities, f and Nu, have to be combined somehow. From a thermodynamics point of view, there is a reasonable alternative： Since all losses become manifest in corresponding entropy generation rates, these rates are determined in the velocity as well as in the temperature field. Based on the integration of the entropy generation fields, an energy devaluation number is introduced. It basically determines how much oftbe so-called entropic potential of the energy involved in a convective heat transfer process is used within it. This approach is called SLA （second law analysis）.
