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production of oil and gas, oil and gas equipment, it is expedient
to replace existing objects with their models or use modeling
method.
Process of modeling includes following stages: defining of
task, creating or choosing of a model, researching of the model,
transfer of knowledge from the object to model.
The main stage is creating or choosing of a model.
Implementation of this phase is possible only by compliance
with laws of similarities. Physical phenomena (or processes)
called similarity, when appropriate dimensionless complexes for
them are the same, though phenomena have different numerical
values of defining parameters.
Similarity of phenomena and processes are characterized
by numerous and functional compliance of variables, that
participating in the phenomenon or process, and characterize the
model and original objects.
Depending on degree of compliance of model’s parameters
and original object, distinguish the following types of
similarities:
Absolute similarity requires complete identity of states or
phenomena in space and time and relevant parameters.
Full similarity is a similarity of processes or phenomena,
that take place in space and time, which are determined quite
fully to be studied.
Incomplete similarity is connected with the study of
processes only in time or only in space.
Approximate similarity is implemented with some
simplifying assumptions, which leads to inaccuracies, which
must be preliminary assessed.
During the physical modelling of process it is necessary to
provide geometric, temporal and physical similarities [4].

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