###### Abstract
[PERSON] et al. [6] analyzed this particular entrance effect. [PERSON] et al. [7] used the response surface methodology and axisymmetric compressible Euler equations to optimize the nose shape of a train and minimize the tunnel compression wave. More work about nose optimization was conducted by [PERSON] and [PERSON] in [8] and by [PERSON] in [9]. Conventional trains inside tunnels, ETTs, and hyperloops all involve the analysis of moving objects at high speeds within a confined space. In this environment, two main sources provoke drag [10; 11]. One of them is the choking of the flow when the local Mach number reaches its critical level. The second one is the presence of shock waves at transonic and supersonic speeds that travel through the tube. When critical Mach is reached, a high-pressure blockage is generated in front of the capsule, endangering the operability of this system. In this sense, the Hyperloop Alpha [5] proposes two methods to delay both effects in ETT or hyperloop. One method consists of increasing the size of the tube to reduce the blockage ratio of the capsule, which directly affects the cost of the infrastructure. The other is to add a compressor to the vehicle, which will increase the pressure of the swallowed air, preventing its acceleration and choking. The addition of a compressor will allow the use of smaller tunnels before reaching transonic speeds, reducing the cost of the infrastructure. In any case, the tube pressure can be lowered to reduce the impact of transonic patterns. Taking into consideration the pressure as a variable, the ratio between the cross-sectional area of the capsule and the tunnel (known as Blockage Ratio or BR) and the speed of the vehicle, several studies varying these parameters arise [8; 12; 13; 14], including one from the same authors of the present work in [15]. [PERSON] et al. [16] added the effect of the levitating gaps in their confined simulations. Other authors performed similar parametric studies [12], varying pressures, speeds, and diameters. [PERSON] et al. [17] also provided significant conclusions, as they reported that the friction drag is far smaller than the pressure drag. They also noticed that the aerodynamic and pressure drag coefficients do not vary with the tube pressure, but change considerably with the BR. The drag itself varied linearly with the pressure and almost squarely with the train speed. A similar study was performed by [PERSON] [9], who varied the length of the nose to reduce the aerodynamic drag at 0.2 atm and 800 km/h, with a BR of 0.2. [PERSON] et al. [14] analyzed a wide range of pressures, concluding that the pressure drag was significantly affected by the increase in BR. [PERSON] et al. [18] also reported that different operating speeds and working vacuum pressures significantly affected the resistance of the capsule and investigated the head and tail of the train to minimize this force. The connection between the vacuum tubes has also been the object of study by other authors. [PERSON] et al. [19] studied the Pressure Recycle Ducts (PRD) and the influence of the interval length and opening width of PRD on the differential pressure. A similar work was conducted in [4] for the Swissmetro project, which is equivalent to the hyperloop concept. The effect of the temperature in the tube train was studied by [PERSON] et al. [20] at 0.1 atm, from 243 K to 393 K. They reported that supersonic phenomena are more severe when decreasing the temperature, as the Mach number increases at a certain speed, 1000 km/h. High tube temperatures increase the speed of sound, and this reduces the Mach number for the same pod speed, delaying the onset of choking and reducing the aerodynamic drag. However, [PERSON] et al. [14] reported that it is relatively inefficient to increase the tube temperature as a means of reducing the drag. Another field of study was more focused on the wave propagation itself, not only the drag of the vehicle. [PERSON] et al.