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The paper presents mathematical modeling of the distribution of different shapes of red blood cells in plasma. The obtained two-dimensional and three-dimensional tissue models are designed to simulate acoustic response as a result of optoacoustic effect and to calculate the number of red blood cells and determine their shape. The results of mathematical modeling allow preparing the model solutions of blood using polystyrene microspheres. Red blood cells produce quasi-spherical assemblies in different pathologies that occupy a large part of volume (from 30 % to 50 %). The purpose of the research was to simulate spherical aggregates without intersections with the same parameters and unique spatial distribution determined by the structural factor. The main benefit of presented method was investigation of different aggregate compactness with the same size of aggregates containing erythrocytes of different shapes. In the result of 3D computer simulation the total maximum volume fraction of cells was 16 %. The procedure of cells distribution account in aggregates allowed obtaining maximum aggregate compactness ϕi = 40 %.

The paper presents the results of generalization of theoretical and experimental studies of the influence of hydrophysical inhomogeneities on the directional characteristics of the parametric array in the framework of problem solution of improving the efficiency of directional properties of adaptive hydroacoustic systems with parametric emitting arrays. The results of calculations of the directional characteristics of the parametric array obtained on the basis of the Khokhlov-Zabolotskaya-Kuznetsov model are compared with the results of experimental measurements of the directional properties of the parametric array. The normalized dependence of the width of parametric array beam pattern was obtained on the reduction of the difference frequency relative to the central frequency of the pump waves from 5 to 16 times. The influence of the sound velocity change on the direction properties of the parametric array was estimated. The normalized dependence of the width of beam pattern of the parametric array on the value of the sound velocity at the surface of the pump transducer was obtained.