ThermoElectric Rayleigh-Bénard Instability - Revision history

Dyco at 15:02, 1 April 2016

2016-04-01T15:02:47Z

Dyco at 15:01, 1 April 2016

2016-04-01T15:01:40Z

Dyco at 14:59, 30 March 2016

2016-03-30T14:59:32Z

Dyco at 14:59, 30 March 2016

2016-03-30T14:59:10Z

Dyco: Created page with "The situation where a fluid is contained between two plates and heated from below has been extensively studied in the literature from more than a century. The Rayleigh-Bénard..."

2016-03-30T14:57:01Z

Created page with "The situation where a fluid is contained between two plates and heated from below has been extensively studied in the literature from more than a century. The Rayleigh-Bénard..."

New page

The situation where a fluid is contained between two plates and heated from below has been extensively studied in the literature from more than a century. The Rayleigh-Bénard convection (RBC) has shown to be an adequate system for analysing features of fundamental interest, like e.g. turbulence patches, Eckhaus transition, phase diagram or more general dynamical systems behaviour. In the classical approach, boundary conditions are generally considered to be ideal Dirichlet or Neumann, with fixed temperatures for both heat exchangers or a fixed temperature at the top and a fixed heat flux at the bottom. In other words, feedback effects from the working fluids are always considered to be negligible. However as expected, one can observe that local temperature is increasing where the fluid is rising and decreases where the fluid is falling. It has also been shown (Belmonte 1993 PRL) that half of the total temperature difference occurs at the vicinity of the boundary layer and reconnects to the temperature of the bulk, which is almost constant. Consequently the temperature of the heat exchanger cannot be considered independent of time and space. The wall temperatures (i.e. at the wall conditions) are indeed function of the Dirichlet temperature, which is imposed far from the wall, and of the heat flux generated by RBC. Hence, RBC on its own is a good model to explore the general feedback effect of a system by exploring the spatio-temporal modulations of the wall temperature. Moreover, in the presence of charged particles in the bulk of the fluid, the coupling effect of a temperature difference is a voltage difference, namely the thermoelectric effect. One can also expect that the temperature difference, which leads to the RBC, and the modulations due to the feedback, can also generate a dynamical (spatio-temporal) voltage difference. Consequently, we will examine a modified situation and consider a closed loop in a single system (feedback effects) with coupling between a dynamical flow (including heat and mass transfer) and a potential variation.

➢ In collaboration with the DyCoE team, we would like in the long run to examine the three facets of the considered situation. Namely, i) the experimental set-up, that involves to capture possibly very small temperature differences close to the wall; ii) the direct simulation of the whole system (including a Conjugate Heat Transfer approach to the solid-fluid thermal exchange and a model for charged particles multi-component flow ); iii) the design of a reduced simplified semi-analytical toy model, able to mimic the main features of the behaviour.

@@ Line 31: / Line 31: @@
 iii) the design of a reduced simplified semi-analytical toy model, able to mimic the main features of the behavior.
-===''Participants''===
+==''Participants''==
 Eric Herbert, Yves D'Angelo, Christophe Goupil.

@@ Line 1: / Line 1: @@
 The situation where a fluid is contained between two plates and heated from below has been extensively studied in the literature from more than a century.
 The Rayleigh-Bénard convection (RBC) has shown to be an adequate system for analysing features of fundamental interest, like e.g. turbulence patches,
 Eckhaus transition, phase diagram or more general dynamical systems behaviour.
 In the classical approach, boundary conditions are generally considered to be ideal Dirichlet or Neumann, with fixed temperatures for both heat exchangers
 or a fixed temperature at the top and a fixed heat flux at the bottom.
@@ Line 17: / Line 22: @@
 a dynamical flow (including heat and mass transfer) and a potential variation.
-In the long run, we would like to examine the three facets of the considered situation. Namely,
+===''Work-in-progress''===
 i) the experimental set-up, that involves to capture possibly very small temperature differences close to the wall;
@@ Line 23: / Line 29: @@
 ii) the direct simulation of the whole system (including a Conjugate Heat Transfer approach to the solid-fluid thermal exchange and a model for charged particles multi-component flow);
-iii) the design of a reduced simplified semi-analytical toy model, able to mimic the main features of the behaviour.
+iii) the design of a reduced simplified semi-analytical toy model, able to mimic the main features of the behavior.

← Older revision		Revision as of 14:59, 30 March 2016
Line 1:		Line 1:
−	The situation where a fluid is contained between two plates and heated from below has been extensively studied in the literature from more than a century. The Rayleigh-Bénard convection (RBC) has shown to be an adequate system for analysing features of fundamental interest, like e.g. turbulence patches, Eckhaus transition, phase diagram or more general dynamical systems behaviour. In the classical approach, boundary conditions are generally considered to be ideal Dirichlet or Neumann, with fixed temperatures for both heat exchangers or a fixed temperature at the top and a fixed heat flux at the bottom. In other words, feedback effects from the working fluids are always considered to be negligible. However as expected, one can observe that local temperature is increasing where the fluid is rising and decreases where the fluid is falling. It has also been shown (Belmonte 1993 PRL) that half of the total temperature difference occurs at the vicinity of the boundary layer and reconnects to the temperature of the bulk, which is almost constant. Consequently the temperature of the heat exchanger cannot be considered independent of time and space. The wall temperatures (i.e. at the wall conditions) are indeed function of the Dirichlet temperature, which is imposed far from the wall, and of the heat flux generated by RBC. Hence, RBC on its own is a good model to explore the general feedback effect of a system by exploring the spatio-temporal modulations of the wall temperature. Moreover, in the presence of charged particles in the bulk of the fluid, the coupling effect of a temperature difference is a voltage difference, namely the thermoelectric effect. One can also expect that the temperature difference, which leads to the RBC, and the modulations due to the feedback, can also generate a dynamical (spatio-temporal) voltage difference. Consequently, we will examine a modified situation and consider a closed loop in a single system (feedback effects) with coupling between a dynamical flow (including heat and mass transfer) and a potential variation.	+	The situation where a fluid is contained between two plates and heated from below has been extensively studied in the literature from more than a century.
		+	The Rayleigh-Bénard convection (RBC) has shown to be an adequate system for analysing features of fundamental interest, like e.g. turbulence patches,
		+	Eckhaus transition, phase diagram or more general dynamical systems behaviour.

−	➢ In ~~collaboration~~ with the ~~DyCoE team~~, we ~~would like~~ in the long run to examine the three facets of the considered situation. Namely, i) the experimental set-up, that involves to capture possibly very small temperature differences close to the wall; ii) the direct simulation of the whole system (including a Conjugate Heat Transfer approach to the solid-fluid thermal exchange and a model for charged particles multi-component flow ); iii) the design of a reduced simplified semi-analytical toy model, able to mimic the main features of the behaviour.	+	In the classical approach, boundary conditions are generally considered to be ideal Dirichlet or Neumann, with fixed temperatures for both heat exchangers
		+	or a fixed temperature at the top and a fixed heat flux at the bottom.
		+	In other words, feedback effects from the working fluids are always considered to be negligible. However as expected, one can observe that local temperature i
		+	s increasing where the fluid is rising and decreases where the fluid is falling. I
		+	t has also been shown (Belmonte 1993 PRL) that half of the total temperature difference occurs at the vicinity of the boundary
		+	layer and reconnects to the temperature of the bulk, which is almost constant.
		+	Consequently the temperature of the heat exchanger cannot be considered independent of time and space.
		+	The wall temperatures (i.e. at the wall conditions) are indeed function of the Dirichlet temperature, which is imposed far from the wall, and of the heat flux generated by RBC.
		+	Hence, RBC on its own is a good model to explore the general feedback effect of a system by exploring the spatio-temporal modulations of the wall temperature.
		+	Moreover, in the presence of charged particles in the bulk of the fluid, the coupling effect of a temperature difference is a voltage difference, namely the thermoelectric effect.
		+	One can also expect that the temperature difference, which leads to the RBC, and the modulations due to the feedback, can also generate a dynamical (spatio-temporal) voltage difference.
		+	Consequently, we shall examine a modified situation and consider a closed loop in a single system (feedback effects) with coupling between
		+	a dynamical flow (including heat and mass transfer) and a potential variation.
		+
		+	In the long run, we would like to examine the three facets of the considered situation. Namely,
		+
		+	i) the experimental set-up, that involves to capture possibly very small temperature differences close to the wall;
		+
		+	ii) the direct simulation of the whole system (including a Conjugate Heat Transfer approach to the solid-fluid thermal exchange and a model for charged particles multi-component flow);
		+
		+	iii) the design of a reduced simplified semi-analytical toy model, able to mimic the main features of the behaviour.