| OBJECTIVES: To make definite the hydrodynamic properties downstream of the stenostic tubular steady flow in vitro, explain the relationship between the pathological feature of cardiovascular stenostic disease and the characteristics of the marginal hydrodynamic properties, and probe an accurate and pragmatic method to research the cardiovascular hydrodynamic pathogenesis both in vitro and in vivo. DESIGN: An experimental and numerical simulation in vitro study. MATERIALS AND METHODS: (1). Experiment: We investigated four lucite models of acute vascular stenosis (stenostic rate: 40%, 65%, 75% and 85%) in a continuous turbulent steady flow circuit. The flow velocity was changed from 0.40m/s to 2.10m/s in the experiments. The circuit fluid is mixed by water and glycerin (volume water/glycerin=7:3, =3.5 10-3kg/s.m , P =1.01 103kg/m3). (2). The velocity turbulent signals of the particles were measured by laser Doppler anemometer (LDA), particle image velocimetry (PIV) and pulsed Doppler ultrasounds (PDU) differently, and the pressure was recorded by the tube that connected with the model. (3). To compare the local marginal velocity and TSS results between LDA and PIV, get the message of the hydrodynamic properties downstream of the stenostic tubular steady flow. (4). We set up the PDU Spectrum Analysis Method (SAM) based on the PDU Edge Spectrum Detection Method (ESDM) to analysis the PDU velocity spectrum, and calculate the mean velocity and Reynolds normal stress (RNS), to appraise the SAM with PIV. (5). Numerical simulation: we employee the k- model to calculate the velocity, TSS and pressure distributions downstream of the stenosis, and evaluate the simulation with PIV. RESULTS: (1). High correlation between LDA and rule PFV's system is examined along the marginal velocity and TSS downstream of stenosis(r = 0.94 and 0.95 separately). (2). Similar with the distribution of the cardiovascular disease localizations, the persistent low velocity, low TSS and low pressure distribute along the marginal area downstream of the stenosis in all the experiment and numerical simulation results. An enlargement of the flow reversal area companied with the increase of the stenostic ratio, at the same time, the TSS and the pressure decreasedobviously. (3). There is a good correlation between the RNS and TSS in the marginal area downstream of the stenosis, and the correlation formulation is: y(TSS)=0.32x(RNS)+0.08, r=0.92, p<0.01. (4). There exist good liner relationships between the PDU SAM and PIV velocity and RNS measurement results, and the correlation formulation were: y (PIV) = 0.95x(PDU) - 0.02, r = 0.93, p<0.01(velocity); y(PIV) = 1.09e0013x (PDV), r=0.78, p<0.01(RNS), moreover, we evolve a relationship equation to estimate the TSS by the PDU indirectly: y(TSS)=035e0.013x (PDU)+0.08. (5). There were good correlations between the results of the numerical simulation velocity, TSS and pressure and the experiment results in the marginal area downstream of the stenosis. (6). The numerical simulation results make known : local marginal velocity, TSS and pressure of the "Blind area" are decreased further. CONCLUSION: (1). The stenostic model considers the similarity of geometry and physical property of the human cardiovascular system, moreover, it contents the optical and acoustic request of the detection apparatus demand. It's a cheap, convenient and high stability model in the experiment. (2). PIV overcomes the shorts of LDA (for example: LDA detect the velocity point by point, which company with tremendous amount of work), and PIV may become the first way in the cardiovascular hydrodynamics research in vitro. (3). According to the velocity distribution feature, the flow field downstream of the stenosis may be divided into four section: the middle jet area, the flow reversal area, the velocity depart layer and the shear sheet. The length and breadth are decided by the stenostic rate. There exist permanent low velocity, low TSS and low pressure in the flow reversal area. (4). There exist a good relationship...
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