 It is sharing your Chrome window. We are seeing ourselves. You have to go back and choose your PowerPoint from the three options. I'm trying to do that, but I think it's OK. I found that. I found that, yes. So could you see it now? Not yet. It's coming out or something? Yeah, yeah, I think we are there. Yeah, go on. OK. Thank you so much for giving me the chance to present my research here. I want to talk about heat transfer characteristics of non-confined gas medium. And since I can't see the chat section, please ask your question whenever you want. I can't actually see the part that is actually for the chat. First of all, I want to actually explain about the application of the heat conduction in the gas. Non-confined gas medium. One of them is some thermal switch that has been recently in 2018, of course. There is thermal diode, actually, that uses the gas non-confined medium. The other application can be in the field of thermal switch that controls the heat in both directions. And the other is some, actually, new one that is called absorption capillary transition control thermal switch, which uses the gas phase of the, for example, argon and let the heat transfer in only one direction. Beside the application, I think I should explain a bit about the physics of that in the beginning. And the most important, actually, number that we deal with in non-confined gas medium is Knudsen number. It's actually consists of mean free pass divided by characteristic lengths of the channel. Define the Knudsen number. And based on this Knudsen number, we can divide the Floyd flow and heat transfer into different regime. Actually, you can see the classification here. For the continuum flow, we can use, actually, we can solve Euler equation or Navier-Stokes equation. And even for a slip flow, we can actually use the Navier-Stokes with a slip on recondition. When it comes to free molecular flow regime, the heat transfer and Floyd flow can be dealt with, actually, collisionless Boltzmann equation that's a form of the Boltzmann equation, which we omitted the collision part. And about the transition flow, which I have focused, the Bayer-Nett equation is a possible choice. But besides, actually, the Boltzmann equation, which governs here also. But there's some problem about the transition flow. Actually, rarefaction can be dealt with Bayer-Nett equation and Boltzmann equation and this sort of equation that could be solved numerically or even analytically. But there's two other phenomena which can be considered as surface adsorption. The gas adsorbed on the surface of the valve of the channel and valve force field, which cannot ideal, actually, correctly or actually, how can I say? Precisely, we cannot actually model these two phenomena by Bayer-Nett equation or Boltzmann equation. Because of, and in order to solve the problem in this regime, transition flow, which is this Knudsen number is actually 0.1 up to 10, it's better to use molecular dynamics to solve the heat transfer. And Reza, Reza had a question for you. What is the wall made up of, typically? Everything can be made. Some metals I have actually, I will actually talk about it in the next slide. Yeah, go ahead. Thanks. So we use molecular dynamics to actually solve the problem in this region. The surface adsorption is clear. The gas atoms adsorbed on the surface. What's about the valve force field? Valve force field is actually the force that penetrate into the fluid in the order of 1 nanometer and can change the characteristics of fluid in that region. If we deal with liquid, we have density layering that you absolutely know and hear about that. But when it comes to gas, there is only one peak in the density. And the density increased in this 1 nanometer from each wall in this region. The reason refers to the fact that when the gas atoms come actually to this region and collide with the wall, they actually attracted by the absorb actually somehow by the force field that wall atoms create. And due to that, their velocity actually somehow decrease and they accumulated in this region. We could say that somehow the residence time of the gas atoms in that region increases somehow. And so our goal was to find out how can this phenomena increasing the density near the walls affect the thermal resistance of the gas domain. We used such simulation and actually assigned higher temperature to the wall and lower temperature to the bottom wall. The gas molecules are free to move and the wall atoms stick together with some spring somehow. And they vibrate. They produce the temperature. The gas collide with them and the heat is transferred and between these two walls due to actually the conduction. Sorry for the interruption. You're at nine minutes. Basically, we have one minute to your official time and then five more minutes for questions. But it's flexible. Go on. OK, OK. We can see here the result of this phenomenon when the temperature difference is applied on the walls. When it is 200, actually we can see that the bottom wall was the cold wall and the upper wall was the hot wall. It can be seen that when the gas collide the cold wall, actually it loses more energy and it accumulates more near the cold wall. In contrast with the upper wall, that can be seen that when the gas atoms collide it, it actually gains some more energy. I had a clarification. These are doing NVT simulations of this or what? Or NVE? No, it's NVE. At this stage it's NVE and the walls are actually landgevin all applied on the walls. OK, I understand. And the gas is, and no thermostat is applied on the gas. So it's free to interact energy. And this actually density profile will lead to such normalized temperature distribution as can be seen here. Usually in the continuum fluid mechanics, the normalized temperature are the same. The profile is the same. And we don't have this difference. This is occurred due to this density difference that occurs near two walls. And the heat flux is also calculated. And effective thermal conductivity is also calculated from Fourier's law. And we can consider the profile, those temperature profiles, something like this. It has five actually separate regions that can be distinguished here. And we actually somehow calculated the thermal resistance for each of these parts. Actually, you can see that the lowest value goes for the bulk part, C2D. It has the lowest resistance and the interfacial resistance near the cold wall and hot wall can be seen here. And this resistance actually goes back to the wall force field region, the resistance that this region creates itself. So it's actually the main parameter that are effective is one of them is the Knudsen number, which clearly can change the characteristics of gas medium. The other one is temperature of the wall that can be seen, which change the temperature of the wall, can greatly change the thermal resistance. And the other is a wall gas interaction parameter we have used in that study. We have used some simple assumption. Maybe I can refer to that somehow. Like we have to wrap it up. We have a minute to the strict. OK. This assumption was made for the first, actually, our first research. And in the others, we have changed gas Knudsen number, wall temperature, and wall material. I should actually escape them. And these are the person who, which I have worked with them during that project. About the current project I have, I'm working on charged nanoparticle in collaboration with Sami Merabia, Ali Rajapur, and Mohamed Hasan Saidi to see the effect of charge on the nanoparticle, on the viscosity of the flow, and interfacial thermal conductance of fluid and actually the water, which is around that. Thank you so much for your attention. Right, the time is over. Sure, thank you very much for the interesting talk. So I guess Ali said that we leave 30 seconds for the next, but we don't have enough time for questions. I believe there is one question from the audience. I think we better leave it for the break. Thank you very much.