E. M. Colocassides College of Tourism & Hotel Management, Doctor of Science in

Groundwater use in Jizzakh region problem 
Sharof Mamarajabovich Musayev 
Ilyos Ilhom o’g’li Tolliboyev 
Jizzakh Polytechnic Institute 
Abstract: 
In this paper, the pressure loss at the expense of local resistances is 
theoretically investigated by relating it to the velocity before and after the barrier by 
linking it to the flow rate. 
Keywords:
groundwater, pipelines, hydrodynamic science 
Scientific substantiation of the coefficient of local resistance. 
Local resistances include those installed in pipelines and in which there is a 
change in the average speed, both in absolute value, in such a direction. 
Scientific substantiation of the coefficient of local resistance. 
Local resistances are those installed in pipelines and in which the change in 
average velocity occurs both in absolute value and in such a direction. 
Introduction.
The decrease in flow energy is one of the most pressing problems 
of modern hydrodynamic science, and many experimental studies are being carried 
out to solve the problem, and mathematically ready models are being presented. This 
article also discusses some aspects. 
The main part.
Various local artificial barriers can be installed for production 
needs in separate locations of the flow pipes. These obstructions cause sudden abrupt 
contraction and expansion of the tubes, jerks, abrupt turns, diaphragms, etc., 
additional resistance. Where local resistance is encountered in the pipes, the current 
loses part of its energy to overcome this resistance. 
The local resistance is called the local hydraulic resistance because it is located 
at a very short distance from the length of the pipes. Manifestations of local 
resistance occur differently in manufacturing and industrial enterprises, but for all of 
them there is no theoretically separate theory, but to solve the problem H
мах
=
𝜉
𝑉
2
2𝑔 
J.Weisbach's formula is used. The x in the formula is called the local resistance 
coefficient and is based on the notion of how the geometric shape of the local area 
𝑃
1
𝛾
𝑃
2
𝛾
"Science and Education" Scientific Journal / ISSN 2181-0842
December 2021 / Volume 2 Issue 12
www.openscience.uz
238

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resists the current. Unfortunately, scientific research in the field of hydromechanics 
has not found a practical solution. The theoretical results obtained differ from the 
experimental conclusions by a small number of deviations, and the theory has not yet 
been fully resolved. 
The easiest option for research in this field is to find, model, and apply the x-
local resistance coefficient in the laboratory under high-precision to high efficiency in 
manufacturing and industrial plants. Under laboratory conditions, the high x-local 
resistance coefficient is determined as follows. 
The manifestations of local resistance are many and varied, but there is a 
common guideline for all of them. In hydraulic calculations, if the pipe is short and 
the local resistances are large, then the pressure lost for local resistances will be much 
greater than the pressure lost along the length of the channel. 
In this case, local resistance will be important. Of course in hydraulic 
calculations we must take into account these local resistances. If in any section of 
pipe there are several local resistances, of course, local resistances at the point of 
entry, exit of the vessel, exit of the vessel, bend of the pipe at an angle, sudden 
expansion and contraction, the local resistance coefficients of that place are 
determined, the local resistance coefficient of each local equal to the sum of the 
resistance coefficients, viz 
𝜉 = 𝜉
𝑖𝑛𝑡𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛
+ 𝜉
𝑓𝑎𝑢𝑐𝑒𝑡 
+ 𝜉
𝑡𝑢𝑟𝑛 
+ ξ
exit 
In that case the local lost pressure is equal to H
мах
=
Σ𝜉
𝑉
2
2𝑔 
Finding the lost pressure at the expense of local resistances requires theoretical 
knowledge from the researcher, because local resistance reduces the kinetic energy of 
the current by affecting the flow rate. We consider this situation in the following 
experiment. 
It can be seen from these hydrodynamic processes that the velocity of the flow 
in the diameters d
1
and d
2
is different, the difference in velocities gives the pressure 
lost v
1
- v
2
= ∆v. The pressure lost due to the speed difference can be determined as 
follows; 
h
мах
=
(𝑉
1
−𝑉
2
)
2
2𝑔 
=
∆𝑉
2
2𝑔 
where: V
1
- velocity before expansion of the pressure pipe; 
V
2
- the velocity after expansion of the pressure pipe; 
d
1
v
1
 
d
2
v
2
 
"Science and Education" Scientific Journal / ISSN 2181-0842
December 2021 / Volume 2 Issue 12
www.openscience.uz
239

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The difference between these velocities 
v
1 
-
v
2 
=
∆
v
∆𝑉
2
2𝑔 
gives the value of local 
pressure loss. therefore, it gives incorrect conclusions. 
Theoretically, this process can be solved as follows, i.e. the local resistance 
coefficient x at the point where the pipe diameter changes can be calculated 
analytically by the flow velocities v
1
and v
2
, the result giving the same conclusion. 
For example, let's express the process by v
1 
h
мах
=
(𝑉
1
−𝑉
2
)
2
2𝑔 
instead of v
2
in the formula 
we write by v
1
, that is, 
𝜔
1
∗ 𝑣
1
= 𝜔
2
∗ 𝑣
2
= 
𝑄
From the equation 
𝑣
2
=
𝜔
1
𝜔
2
𝑣
1
conditionally, а
𝜔
2
=
𝑣
1
𝑣
2
𝜔
2
) where h
мах
=
(1 −
𝑉
2
𝑉
1
)
𝑉
1
2
2𝑔 
if we define 
𝜉
′
=
(1 −
𝑉
2
𝑉
1
)
2
or h
мах
=
𝜉
′ 𝑉
1
2
2𝑔 
from h
мах
=
(1 −
𝜔
1
𝜔
2
)
2 𝑉
1
2
2𝑔 
if 
𝜉
′
=
(1 −
𝜔
1
𝜔
2
)
2
and 
𝜉
′
=
(1 −
𝜔
1
𝜔
2
)
2
are 
equal to each other. 
In the same way, if we take the velocity v
2
behind the local resistance, then we 
define it as 
𝜉
′′
=
(1 −
𝑉
1
𝑉
2
)
2
then h
мах 
=
𝜉
′′ 𝑉
2
2
2𝑔 
or if h
мах
=
(1 −
𝜔
2
𝜔
1
)
2 𝑉
2
2
2𝑔 
h
мах 
=
𝜉
′′ 𝑉
2
2
2𝑔 
. 
𝜉
′′
=
(1 −
𝑉
1
𝑉
2
)
2
=
(1 −
𝜔
2
𝜔
1
)
2
, h
мах 
=
𝜉
′′ 𝑉
2
2
2𝑔 
We expressed the lost 
pressure by velocity v
2
. The results obtained give the same value. 
h
мах
=
𝜉
′ 𝑉
1
2
2𝑔 
=
𝜉
′′ 𝑉
2
2
2𝑔 
due to the difference in velocities 
𝜉
′
and 
𝜉
′′
. The analytical solution fully 
confirms the experimental data. 
Conclusion. If we examine the research in this area in relation to the Reynolds 
number, there are changes in the values of 
𝜉
′
and 
𝜉
′′
, the main reason being that the 
Reynolds number increases at high flow velocities, which in turn affects the 
coefficients 
𝜉
′
and 
𝜉
′′
. Research in this area is awaiting a solution, both theoretically 
and practically.