Examples of solved tasks
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Flow modeling in contact tanks
Objective: to Calculate the flow of viscous incompressible fluid in the tank in order to determine the flow pattern, the time of passage of liquid particles along trajectories inside the structure.
Characteristics: The tank is considered to be completely filled with liquid to the level of the media interface in a resting state, so that there is no free surface. There is no overflow channel. The processes in the supply pipe for the ozone-water mixture are not modeled. The supply pipe for the ozone-water mixture is geometrically simplified in the channel region.
Summary: Distributions of hydrodynamic parameters inside the tank (velocity fields, concentrations) are obtained. Estimates are obtained for the time of finding a liquid particle in the computational domain. During the first 6 minutes, the flow rate at the output is zero, followed by a sharp increase, followed by a more gradual drop in flow rate. It is worth noting that 50% of the mass of the impurity is removed within 18 minutes, 75% - within 27 minutes, 90% - within 37 minutes.
Characteristics: The tank is considered to be completely filled with liquid to the level of the media interface in a resting state, so that there is no free surface. There is no overflow channel. The processes in the supply pipe for the ozone-water mixture are not modeled. The supply pipe for the ozone-water mixture is geometrically simplified in the channel region.
Summary: Distributions of hydrodynamic parameters inside the tank (velocity fields, concentrations) are obtained. Estimates are obtained for the time of finding a liquid particle in the computational domain. During the first 6 minutes, the flow rate at the output is zero, followed by a sharp increase, followed by a more gradual drop in flow rate. It is worth noting that 50% of the mass of the impurity is removed within 18 minutes, 75% - within 27 minutes, 90% - within 37 minutes.
Modeling of soils
Objective: To determine the areas of cracks in the short-term loading of the mine plug in the flooding of production, modeling the growth of cracks in the long-term loading, optimization of the shape of the mine plug.
Characteristics: The complexity of the problem consisted in the substantial nonlinearity of the rock model and the study of the solution for grid convergence, which led to large dimensions of the grid model. The influence of conditions on the contact boundary was also investigated.
Summary: The optimization of the shape of the cork is carried out. The optimal topology forms a shaft tube, which exclude the nucleation of cracks in the rock under short-term loading. The study of the behavior of rocks under sustained loading
Characteristics: The complexity of the problem consisted in the substantial nonlinearity of the rock model and the study of the solution for grid convergence, which led to large dimensions of the grid model. The influence of conditions on the contact boundary was also investigated.
Summary: The optimization of the shape of the cork is carried out. The optimal topology forms a shaft tube, which exclude the nucleation of cracks in the rock under short-term loading. The study of the behavior of rocks under sustained loading
Building block analysis
Objective: Calculation of damages in the overlap of monolithic reinforced concrete obtained because of falling concrete block.
Characteristics: The size of the overlap in the plan is 21.7 * 42.4m. It consists of a reinforced concrete slab with h = 500mm with a span between the columns 8700mm, reinforced concrete beams of rectangular cross-section 900 * 1500mm, multilayered operational coating consisting of 2 layers of polystyrene foam h = 20mm, layer polystyrene foam h = 50mm, concrete screed h = 150mm, a layer of sand h = 300mm, a layer of reinforced concrete slabs h = 180mm. The floor slab, columns and joists are made of concrete B40.
Summary: The deformations of the reinforcement are elastic; the width of the crack opening lies in the permissible region. Damage to the main structure is minor - the design can be used without dismantling.
Characteristics: The size of the overlap in the plan is 21.7 * 42.4m. It consists of a reinforced concrete slab with h = 500mm with a span between the columns 8700mm, reinforced concrete beams of rectangular cross-section 900 * 1500mm, multilayered operational coating consisting of 2 layers of polystyrene foam h = 20mm, layer polystyrene foam h = 50mm, concrete screed h = 150mm, a layer of sand h = 300mm, a layer of reinforced concrete slabs h = 180mm. The floor slab, columns and joists are made of concrete B40.
Summary: The deformations of the reinforcement are elastic; the width of the crack opening lies in the permissible region. Damage to the main structure is minor - the design can be used without dismantling.
Crack resistance of metal structures
Objective: Evaluation of the characteristics of crack resistance of node columns sports long-span structures
Characteristics: The top assembly of the columns of a sport large-span structure is a welded mix of blooms (the main power element), the insert plate, the side fins and the base. The assembly is made of construction steel C345 GOST 27772-88, the weld joints are equal to 16 ... 20 mm
Summary: The possibility of forming an elliptical crack in the weld zone of the object under consideration with depths from 1 to 14 mm has been revealed. At best, the crack creates a situation dangerous for the further operation of the structure, at worst - the state of the object is considered critical, in which the column collapses. The presence of cracks significantly reduces the life cycle of the structure
Characteristics: The top assembly of the columns of a sport large-span structure is a welded mix of blooms (the main power element), the insert plate, the side fins and the base. The assembly is made of construction steel C345 GOST 27772-88, the weld joints are equal to 16 ... 20 mm
Summary: The possibility of forming an elliptical crack in the weld zone of the object under consideration with depths from 1 to 14 mm has been revealed. At best, the crack creates a situation dangerous for the further operation of the structure, at worst - the state of the object is considered critical, in which the column collapses. The presence of cracks significantly reduces the life cycle of the structure
Modification of antenna posts design
Objective: Calculation of natural frequencies of antenna frame in the range from 0 to 20 Hz.
Characteristics: The design of the antenna post is a beam structure and consists of three nodes: the base, the container and the antenna support. Four support beams support the base. The container is installed on the base with two horizontal beams. The container and the base of the antenna are not connected. On the roof of the container is installed pentagon from the channels, on which the fairing antenna is fixed. This fairing is not connected to the antenna and is not taken into account in the model.
Summary: The calculations showed that the frequencies corresponding to the "container" waveforms exceed 5 Hz, satisfying the requirement. However, in both initial versions - "light" and "heavy" - there are frequencies of 5-7 Hz, corresponding to the flexural oscillations of the antenna support with an antenna installed on it. Design modifications without significant redesign do not allow raising these frequencies to 15 Hz.
Characteristics: The design of the antenna post is a beam structure and consists of three nodes: the base, the container and the antenna support. Four support beams support the base. The container is installed on the base with two horizontal beams. The container and the base of the antenna are not connected. On the roof of the container is installed pentagon from the channels, on which the fairing antenna is fixed. This fairing is not connected to the antenna and is not taken into account in the model.
Summary: The calculations showed that the frequencies corresponding to the "container" waveforms exceed 5 Hz, satisfying the requirement. However, in both initial versions - "light" and "heavy" - there are frequencies of 5-7 Hz, corresponding to the flexural oscillations of the antenna support with an antenna installed on it. Design modifications without significant redesign do not allow raising these frequencies to 15 Hz.
Simulation of flow in the gas outlet
Objective: Determination of the hydraulic resistance of the simplified geometry of the gas outlet of the gas turbine engine of the offshore gas turbine generator.
Characteristics: As a model of turbulence was taken SST-model Menter, taking into account the influence of the work of viscous forces. The adhesion condition was assumed on the walls of the gas outlet. The heat exchange with the outer surface and the internal elements was not taken into account. The calculation was made in a steady-state formulation for the initial approximation. Then unsteady calculation with an adaptive time step corresponding to the Courant number equal to 30 was made.
Summary: Total pressure losses in the gas outlet are determined
Characteristics: As a model of turbulence was taken SST-model Menter, taking into account the influence of the work of viscous forces. The adhesion condition was assumed on the walls of the gas outlet. The heat exchange with the outer surface and the internal elements was not taken into account. The calculation was made in a steady-state formulation for the initial approximation. Then unsteady calculation with an adaptive time step corresponding to the Courant number equal to 30 was made.
Summary: Total pressure losses in the gas outlet are determined
Determination of towing resistance of a ship
Objective: To determine the values of towing resistance of ships.
Summary: The influence of the initial turbulence level of the flow on the value of towing resistance of ships is analyzed. The technique of determining the towing resistance of a vessel based on three-dimensional modeling of vessel traffic was developed and verified on the basis of experimental data.
Summary: The influence of the initial turbulence level of the flow on the value of towing resistance of ships is analyzed. The technique of determining the towing resistance of a vessel based on three-dimensional modeling of vessel traffic was developed and verified on the basis of experimental data.
Flow modeling in a vortex reactor
Objective: Modeling the flow of water in a hydrodynamic reactor, both without taking into account the particles of the reagent, and in complete formulation, taking into account the final concentration of the particles and their reverse effect on the flow.
Characteristics: A fine suspension of calcite or marble is additionally supplied to water, after the introduction of a reagent that causes the crystallization of calcium hydrogen carbonate. The particles are introduced suspensions serve as centers of crystallization, which provides the allocation of the calcium water with a minimum displacement of interfacial equilibrium. If the particle size of the suspension and the flow are correctly selected, starting from a certain section, the vertical component of the flow velocity becomes smaller than the settling velocity of the particles, so that the particles do not enter the upper part of the reactor, which allows to remove soft water without particles from it.
Summary: It has been found that flow patterns are organized inefficiently for given fluid flow rates and characteristic particle sizes. Most of the reagent accumulates in the lower region of the reactor and does not participate in water purification
Characteristics: A fine suspension of calcite or marble is additionally supplied to water, after the introduction of a reagent that causes the crystallization of calcium hydrogen carbonate. The particles are introduced suspensions serve as centers of crystallization, which provides the allocation of the calcium water with a minimum displacement of interfacial equilibrium. If the particle size of the suspension and the flow are correctly selected, starting from a certain section, the vertical component of the flow velocity becomes smaller than the settling velocity of the particles, so that the particles do not enter the upper part of the reactor, which allows to remove soft water without particles from it.
Summary: It has been found that flow patterns are organized inefficiently for given fluid flow rates and characteristic particle sizes. Most of the reagent accumulates in the lower region of the reactor and does not participate in water purification
Determination of brine distribution time
Objective: Determination of brine distribution time.
Difficulties:
Decision: Creation of brine distribution patterns under various uncertainty conditions
Summary: Determined by the time distribution of the brine to develop. Recommendations on prevention of flooding of development are given.
Difficulties:
- High dimensionality of the problem
- Long time 3D hydrodynamic calculations
- Taking into account uncertainties of rock formation properties and configuration
- Accounting for salt dissolution process
Decision: Creation of brine distribution patterns under various uncertainty conditions
Summary: Determined by the time distribution of the brine to develop. Recommendations on prevention of flooding of development are given.
Horizontal quenching
Objective: Determination of the values of warping of the sample during the quenching and residual stresses
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