Can my boyfriend forgive me for going to the foot bath center
Publish: 2021-05-22 18:30:25
1. There are all the major cities. You can consult the guard about the professional trainer forging. After you find it, there will be a melting pot next to it. Other friendly towns on the map usually have melting pots
2. How did you know that?
3. As a man, I think your worry is superfluous. You care about your husband very much. There are several bad men in the world. A man is like a handful of sand. The more you grasp the date, the less space you lose. If you are my girlfriend, I hope you will be understanding. As long as I cheat, I hope you will be suspicious, You should also know what kind of person your boyfriend is. People want to be trusted. Only when you understand and tolerate can you be happy. You should use your brain to think about how to make him inseparable from you. How can you let him see other girls without looking at them? Because at that time, he knew in his heart that he had a good wife. I hope you will be happy. I hope there will be lovers in the world and they will get married
4. Hydromechanics includes statics and dynamics
I. Basic Equations of hydrostatics
(I) derivation of basic equations of hydrostatics:
1. Gravity: F
=
A (z1 -
Z2) ρ G
direction downward
2. Pressure acting on the upper surface: F1
=
P1
a
direction downward
3. Pressure acting on the lower surface: F2
=
P2
a
direction upward
F +
F1 +
F2
=
0
P2
=
P1
+ (z1 -
Z2) ρ G
... ① if the liquid column is moved upward to the liquid level, and the pressure above the liquid level is P0, the height difference of the liquid column Z1 -
Z2
= h, the depth of the lower surface from the liquid level, the above formula can be rewritten as:
P2 =
P0
+ H ρ g……②
P2=
h ρ G... ③
①, ② and ③ are the basic equations of statics< Second, fluid dynamics Bernoulli equation
the idea of Bernoulli equation derivation is: starting from the actual needs of solving fluid flow problems, the graal simplification method is adopted: total energy balance of flow system (including internal energy and heat energy) - → mechanical energy balance of flow system - → mechanical energy balance of incompressible fluid steady flow< (1) derivation of Bernoulli equation:
balance calculation range:
balance calculation datum:
datum horizontal plane:
1. Energy of flowing fluid J / kg
2. Law of conservation of energy
according to the first law of thermodynamics, the energy balance calculation formula of 1kg fluid based continuous steady flow system is:
z1g
+ U12 / 2 + P1 /
ρ< br />+We
=
Z2g
+u22/2+p2/
ρ< br />+ Σ HF
(1-19)
in the formula, V
-- specific volume of fluid, m3 / kg
formula (1-19) and formula (1-19a) are the total energy balance formula of steady flow process and the expression of the first law of thermodynamics of flow system
pay attention to understand the concept of static pressure energy (PV): the work required to send 1kg fluid into the system, also known as flow work.
I. Basic Equations of hydrostatics
(I) derivation of basic equations of hydrostatics:
1. Gravity: F
=
A (z1 -
Z2) ρ G
direction downward
2. Pressure acting on the upper surface: F1
=
P1
a
direction downward
3. Pressure acting on the lower surface: F2
=
P2
a
direction upward
F +
F1 +
F2
=
0
P2
=
P1
+ (z1 -
Z2) ρ G
... ① if the liquid column is moved upward to the liquid level, and the pressure above the liquid level is P0, the height difference of the liquid column Z1 -
Z2
= h, the depth of the lower surface from the liquid level, the above formula can be rewritten as:
P2 =
P0
+ H ρ g……②
P2=
h ρ G... ③
①, ② and ③ are the basic equations of statics< Second, fluid dynamics Bernoulli equation
the idea of Bernoulli equation derivation is: starting from the actual needs of solving fluid flow problems, the graal simplification method is adopted: total energy balance of flow system (including internal energy and heat energy) - → mechanical energy balance of flow system - → mechanical energy balance of incompressible fluid steady flow< (1) derivation of Bernoulli equation:
balance calculation range:
balance calculation datum:
datum horizontal plane:
1. Energy of flowing fluid J / kg
2. Law of conservation of energy
according to the first law of thermodynamics, the energy balance calculation formula of 1kg fluid based continuous steady flow system is:
z1g
+ U12 / 2 + P1 /
ρ< br />+We
=
Z2g
+u22/2+p2/
ρ< br />+ Σ HF
(1-19)
in the formula, V
-- specific volume of fluid, m3 / kg
formula (1-19) and formula (1-19a) are the total energy balance formula of steady flow process and the expression of the first law of thermodynamics of flow system
pay attention to understand the concept of static pressure energy (PV): the work required to send 1kg fluid into the system, also known as flow work.
5. Surface force. Mass force, also known as physical force, refers to the force that does not pass through the medium and acts directly on the material, such as gravitation, electromagnetic force, centrifugal force, etc.. Obviously, friction is proced when the medium is in relative displacement, so it is definitely not mass force.
6. V = (2GH) ^ (1 / 2) / (1 + L / D + J) ^ (1 / 2)
where: h -- water head, m; G -- acceleration of gravity, M / S ^ 2; Inlet - resistance coefficient along the pipeline; L -- pipe length, m; D -- pipe diameter, m; J -- local resistance coefficient.
where: h -- water head, m; G -- acceleration of gravity, M / S ^ 2; Inlet - resistance coefficient along the pipeline; L -- pipe length, m; D -- pipe diameter, m; J -- local resistance coefficient.
7. Relative pressure, also known as gauge pressure. The local atmospheric pressure was set at 0
when calculating the relative pressure, it is not necessary to calculate the atmospheric pressure
when calculating absolute pressure, atmospheric pressure should be calculated
when calculating the difference between the two pressures, the atmospheric pressure can be ignored.
when calculating the relative pressure, it is not necessary to calculate the atmospheric pressure
when calculating absolute pressure, atmospheric pressure should be calculated
when calculating the difference between the two pressures, the atmospheric pressure can be ignored.
8. Hello
well, if I understand correctly, what you are asking is the normal stress and shear stress of fluid
normal stress refers to a force proced by a flow block in a fluid e to the pressure of the surrounding fluid. You must know that fluid (such as water) will proce hydraulic pressure. If the hydraulic pressure given to a flow block from the outside is negative, then the flow block will be subject to tensile force; If the hydraulic pressure is positive, the flow block is compressed. Generally, we think that the pressure is perpendicular to the surface of the flow block (this kind of fluid is called barotropic fluid). The effect of normal stress is to compress or expand the volume of the flow block, which is also one of the causes of fluid flow
in some cases, the volume of fluid hardly changes under the action of pressure, that is, normal stress, so people approximately think that this fluid is an incompressible fluid (such as water)
shear stress is a kind of force proced by a flow block in a fluid e to the viscosity of the surrounding fluid. Any common fluid is viscous, which is the main reason why ships encounter resistance when sailing in water. The effect of this force is shear, which is like turning a square into a parallelogram. Shear stress generally acts on the tangent direction of the flow block surface, which makes the flow block deform continuously in the process of motion (most fluids will deform under any shear stress, which is called Newtonian fluid). The shear stress caused by viscosity brings many complex problems to the calculation of fluid mechanics, which have not been solved yet
in some cases, the viscosity of fluid is very small, or plays a little role (for example, in the turbulent River), people will ignore the shear stress caused by viscosity to simplify the calculation, this kind of fluid is called inviscid fluid
hope to help you Hand only)
well, if I understand correctly, what you are asking is the normal stress and shear stress of fluid
normal stress refers to a force proced by a flow block in a fluid e to the pressure of the surrounding fluid. You must know that fluid (such as water) will proce hydraulic pressure. If the hydraulic pressure given to a flow block from the outside is negative, then the flow block will be subject to tensile force; If the hydraulic pressure is positive, the flow block is compressed. Generally, we think that the pressure is perpendicular to the surface of the flow block (this kind of fluid is called barotropic fluid). The effect of normal stress is to compress or expand the volume of the flow block, which is also one of the causes of fluid flow
in some cases, the volume of fluid hardly changes under the action of pressure, that is, normal stress, so people approximately think that this fluid is an incompressible fluid (such as water)
shear stress is a kind of force proced by a flow block in a fluid e to the viscosity of the surrounding fluid. Any common fluid is viscous, which is the main reason why ships encounter resistance when sailing in water. The effect of this force is shear, which is like turning a square into a parallelogram. Shear stress generally acts on the tangent direction of the flow block surface, which makes the flow block deform continuously in the process of motion (most fluids will deform under any shear stress, which is called Newtonian fluid). The shear stress caused by viscosity brings many complex problems to the calculation of fluid mechanics, which have not been solved yet
in some cases, the viscosity of fluid is very small, or plays a little role (for example, in the turbulent River), people will ignore the shear stress caused by viscosity to simplify the calculation, this kind of fluid is called inviscid fluid
hope to help you Hand only)
9. How to find the tangential unit vector of a curve in fluid mechanics
surface force refers to the force acting on the outer surface of a fluid which is proportional to the surface area. Surface tension is a kind of surface force, which is the pulling force acting on the free surface of a fluid along the normal direction of the action surface.
surface force refers to the force acting on the outer surface of a fluid which is proportional to the surface area. Surface tension is a kind of surface force, which is the pulling force acting on the free surface of a fluid along the normal direction of the action surface.
10. It can be divided into two parts: to plane or to surface
(1) to plane
force = pressure at the center of mass of plane × The area of the plane
(note; Pressure at the center of mass of the plane = depth at the center of mass × The specific gravity of the liquid. Plane area refers to the area submerged by liquid)
(2) curved surface is divided into two-dimensional cylindrical surface and three-dimensional curved surface
1) horizontal force on two-dimensional cylindrical surface (the cylindrical surface is perpendicular to the paper surface)
the projection area of the cylindrical surface projected horizontally onto the side elevation × The pressure at the center of mass of the projected area
vertical force = the weight of the liquid supported by the cylindrical surface
total force = the vector sum of horizontal force and vertical force
(Note: side elevation refers to the surface perpendicular to both the paper and the ground. Surface area refers to the area submerged by liquid)
2) for three-dimensional surface,
horizontal force in left and right directions = the projected area of the surface projected horizontally onto the side elevation × The pressure at the centroid of the projected area
the horizontal force in the inner and outer directions = the projected area of the surface projected horizontally onto the paper × The pressure at the center of mass of the projected area
vertical force = the weight of the liquid supported by the curved cylinder
total force = the vector sum of left and right horizontal force, inner and outer horizontal force and vertical force
(Note: inside out direction refers to the direction perpendicular to the paper)
(1) to plane
force = pressure at the center of mass of plane × The area of the plane
(note; Pressure at the center of mass of the plane = depth at the center of mass × The specific gravity of the liquid. Plane area refers to the area submerged by liquid)
(2) curved surface is divided into two-dimensional cylindrical surface and three-dimensional curved surface
1) horizontal force on two-dimensional cylindrical surface (the cylindrical surface is perpendicular to the paper surface)
the projection area of the cylindrical surface projected horizontally onto the side elevation × The pressure at the center of mass of the projected area
vertical force = the weight of the liquid supported by the cylindrical surface
total force = the vector sum of horizontal force and vertical force
(Note: side elevation refers to the surface perpendicular to both the paper and the ground. Surface area refers to the area submerged by liquid)
2) for three-dimensional surface,
horizontal force in left and right directions = the projected area of the surface projected horizontally onto the side elevation × The pressure at the centroid of the projected area
the horizontal force in the inner and outer directions = the projected area of the surface projected horizontally onto the paper × The pressure at the center of mass of the projected area
vertical force = the weight of the liquid supported by the curved cylinder
total force = the vector sum of left and right horizontal force, inner and outer horizontal force and vertical force
(Note: inside out direction refers to the direction perpendicular to the paper)
Hot content